diff --git a/lib/gcr.rb b/lib/gcr.rb
index bb1f1b4..a83e25d 100644
--- a/lib/gcr.rb
+++ b/lib/gcr.rb
@@ -39,6 +39,18 @@ def cassette_dir
     @cassette_dir || (raise ConfigError, "no cassette dir configured")
   end
 
+  # Specify if cassettes should be compressed to zz
+  def compress=(boolean)
+    @compress = boolean
+  end
+
+  # Whether cassettes should be compressed to zz
+  #
+  # Returns a boolean
+  def compress?
+    @compress ||= false
+  end
+
   # Specify the stub to intercept calls to.
   #
   # stub - A GRPC::ClientStub instance.
@@ -84,7 +96,7 @@ def cassette
   # Returns nothing.
   def with_cassette(name, &blk)
     @cassette = Cassette.new(name)
-    if @cassette.exist?
+    if @cassette.exist? && ENV['GCR_RECORD'].nil?
       @cassette.play(&blk)
     else
       @cassette.record(&blk)
diff --git a/lib/gcr/cassette.rb b/lib/gcr/cassette.rb
index d34e6c6..b403a2c 100644
--- a/lib/gcr/cassette.rb
+++ b/lib/gcr/cassette.rb
@@ -2,6 +2,7 @@ class GCR::Cassette
   VERSION = 2
 
   attr_reader :reqs
+  attr_accessor :reqs_calls_counts
 
   # Delete all recorded cassettes.
   #
@@ -18,8 +19,9 @@ def self.delete_all
   #
   # Returns nothing.
   def initialize(name)
-    @path = File.join(GCR.cassette_dir, "#{name}.json")
+    @path = File.join(GCR.cassette_dir, "#{name}.json#{".zz" if GCR.compress?}")
     @reqs = []
+    @reqs_calls_counts = {}
   end
 
   # Does this cassette exist?
@@ -33,7 +35,8 @@ def exist?
   #
   # Returns nothing.
   def load
-    data = JSON.parse(File.read(@path))
+    json_data = @path.ends_with?(".zz") ? Zlib::Inflate.inflate(File.read(@path)) : File.read(@path)
+    data = JSON.parse(json_data)
 
     if data["version"] != VERSION
       raise "GCR cassette version #{data["version"]} not supported"
@@ -48,11 +51,14 @@ def load
   #
   # Returns nothing.
   def save
-    File.open(@path, "w") do |f|
-      f.write(JSON.pretty_generate(
-        "version" => VERSION,
-        "reqs" => reqs,
-      ))
+    json_content = JSON.pretty_generate(
+      "version" => VERSION,
+      "reqs" => reqs
+    )
+    if GCR.compress?
+      File.write(@path, Zlib::Deflate.deflate(json_content), encoding: "ascii-8bit")
+    else
+      File.write(@path, json_content)
     end
   end
 
@@ -81,32 +87,39 @@ def start_recording
       alias_method :orig_request_response, :request_response
 
       def request_response(*args, return_op: false, **kwargs)
+        req = GCR::Request.from_proto(*args)
         if return_op
-          # capture the operation
-          operation = orig_request_response(*args, return_op: return_op, **kwargs)
-
-          # capture the response
-          resp = orig_request_response(*args, return_op: false, **kwargs)
-
-          req = GCR::Request.from_proto(*args)
-          if GCR.cassette.reqs.none? { |r, _| r == req }
-            GCR.cassette.reqs << [req, GCR::Response.from_proto(resp)]
+          # captures the operation
+          operation = orig_request_response(*args, return_op: true, **kwargs)
+
+          stub = self
+          operation.define_singleton_method(:execute) do
+            # performs the operation (actual API call) and captures the response
+            begin
+              resp = stub.orig_request_response(*args, return_op: false, **kwargs)
+              GCR.cassette.save_interaction(req, resp)
+              resp
+            rescue => resp
+              GCR.cassette.save_interaction(req, resp)
+              raise resp
+            end
           end
 
           # then return it
           operation
         else
-          orig_request_response(*args, return_op: return_op, **kwargs).tap do |resp|
-            req = GCR::Request.from_proto(*args)
-            if GCR.cassette.reqs.none? { |r, _| r == req }
-              GCR.cassette.reqs << [req, GCR::Response.from_proto(resp)]
-            end
-          end
+          resp = orig_request_response(*args, return_op: return_op, **kwargs)
+          GCR.cassette.save_interaction(req, resp)
+          resp
         end
       end
     end
   end
 
+  def save_interaction(req, resp)
+    GCR.cassette.reqs << [req, GCR::Response.from_proto(resp)]
+  end
+
   def stop_recording
     GCR.stub.class.class_eval do
       alias_method :request_response, :orig_request_response
@@ -122,30 +135,54 @@ def start_playing
 
       def request_response(*args, return_op: false, **kwargs)
         req = GCR::Request.from_proto(*args)
-        GCR.cassette.reqs.each do |other_req, resp|
-          if req == other_req
-
-            # check if our request wants an operation returned rather than the response
-            if return_op
-              # if so, collect the original operation
-              operation = orig_request_response(*args, return_op: return_op, **kwargs)
-
-              # hack the execute method to return the response we recorded
-              operation.define_singleton_method(:execute) { return resp.to_proto }
-
-              # then return it
-              return operation
-            else
-              # otherwise just return the response
-              return resp.to_proto
-            end
+
+        # check if our request wants an operation returned rather than the response
+        if return_op
+          # if so, collect the original operation
+          operation = orig_request_response(*args, return_op: return_op, **kwargs)
+
+          # hack the execute method to return the response we recorded
+          operation.define_singleton_method(:execute) do
+            GCR.cassette.read_recorded_response(req).to_proto
           end
+
+          # then return it
+          operation
+        else
+          # otherwise just return the response
+          GCR.cassette.read_recorded_response(req).to_proto
         end
-        raise GCR::NoRecording
       end
     end
   end
 
+  def read_recorded_response(req)
+    interactions = reqs.select { |persisted_req, _| req == persisted_req }
+    resp = interactions[calls_count(req)]&.last
+    iterate_calls_count(req)
+    if resp.nil?
+      raise_error(req, interactions: interactions)
+    end
+
+    resp
+  end
+
+  def calls_count(req)
+    reqs_calls_counts[req.to_h] ||= 0
+  end
+
+  def iterate_calls_count(req)
+    reqs_calls_counts[req.to_h] += 1
+  end
+
+  def raise_error(req, interactions:)
+    calls_count = calls_count(req)
+    raise GCR::NoRecording.new(["Unrecorded request :",
+      "called #{calls_count} #{(calls_count > 1) ? "times" : "time"}, (recorded #{interactions.size})",
+      req.class_name,
+      req.body].join("\n"))
+  end
+
   def stop_playing
     GCR.stub.class.class_eval do
       alias_method :request_response, :orig_request_response
diff --git a/lib/gcr/request.rb b/lib/gcr/request.rb
index 4679d8f..e17a4cb 100644
--- a/lib/gcr/request.rb
+++ b/lib/gcr/request.rb
@@ -1,7 +1,7 @@
 class GCR::Request
   def self.from_proto(route, proto_req, *_)
     new(
-      "route"      => route,
+      "route" => route,
       "class_name" => proto_req.class.name,
       "body"       => proto_req.to_json(emit_defaults: true),
     )
@@ -9,7 +9,7 @@ def self.from_proto(route, proto_req, *_)
 
   def self.from_hash(hash_req)
     new(
-      "route"      => hash_req["route"],
+      "route" => hash_req["route"],
       "class_name" => hash_req["class_name"],
       "body"       => hash_req["body"],
     )
@@ -18,9 +18,9 @@ def self.from_hash(hash_req)
   attr_reader :route, :class_name, :body
 
   def initialize(opts)
-    @route      = opts["route"]
+    @route = opts["route"]
     @class_name = opts["class_name"]
-    @body       = opts["body"]
+    @body = opts["body"]
   end
 
   def parsed_body
@@ -31,6 +31,10 @@ def to_json(*_)
     JSON.dump("route" => route, "class_name" => class_name, "body" => body)
   end
 
+  def to_h
+    {"route" => route, "class_name" => class_name, "body" => body}
+  end
+
   def to_proto
     [route, Object.const_get(class_name).decode_json(body)]
   end
diff --git a/lib/gcr/response.rb b/lib/gcr/response.rb
index d71d9a4..6624c20 100644
--- a/lib/gcr/response.rb
+++ b/lib/gcr/response.rb
@@ -1,8 +1,18 @@
 class GCR::Response
+  GOOGLE_ADS_ERROR_CLASS = 'Google::Ads::GoogleAds::Errors::GoogleAdsError'.freeze
+
   def self.from_proto(proto_resp)
+    class_name = proto_resp.class.name
+
+    body = if class_name == GOOGLE_ADS_ERROR_CLASS
+      proto_resp.failure.to_json(emit_defaults: true)
+    else
+      proto_resp.to_json(emit_defaults: true)
+    end
+
     new(
-      "class_name" => proto_resp.class.name,
-      "body"       => proto_resp.to_json(emit_defaults: true)
+      "class_name" => class_name,
+      "body"       => body
     )
   end
 
@@ -29,6 +39,11 @@ def to_json(*_)
   end
 
   def to_proto
-    Object.const_get(class_name).decode_json(body)
+    if class_name == GOOGLE_ADS_ERROR_CLASS
+      failure = Google::Ads::GoogleAds.const_get(GoogleApi::VERSION)::Errors::GoogleAdsFailure.decode_json(body)
+      raise Google::Ads::GoogleAds::Errors::GoogleAdsError.new(failure)
+    else
+      Object.const_get(class_name).decode_json(body)
+    end
   end
 end