diff --git a/CHANGELOG.md b/CHANGELOG.md
index ee59ec8..38b98f8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,11 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.1.0/) and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [4.0.5](https://github.com/unzerdev/magento2/compare/4.0.4..4.0.5)
+### Fixed
+*  Fix customerId assignment for guest customers in UPL payment methods
+*  Fix and improve salutation handling logic
+
 ## [4.0.4](https://github.com/unzerdev/magento2/compare/4.0.3..4.0.4)
 ### Fixed
 *  Resolve issue with customer company information mapping
diff --git a/Helper/Order.php b/Helper/Order.php
index 9353bfe..62633de 100644
--- a/Helper/Order.php
+++ b/Helper/Order.php
@@ -341,7 +341,11 @@ public function createCustomerFromQuote(Quote $quote, string $email, bool $creat
             ->setFirstname($billingAddress->getFirstname())
             ->setLastname($billingAddress->getLastname());
 
-        $customer->setSalutation($this->getSalutationFromQuote($quote));
+        $customer->setSalutation(
+            $this->getSalutationFromPrefix($billingAddress->getPrefix())
+            ?? $this->getSalutationFromQuote($quote)
+        );
+
         $customer->setEmail($email);
         $customer->setPhone($billingAddress->getTelephone());
         $customer->setBirthDate($quote->getCustomer()->getDob());
@@ -419,12 +423,12 @@ public function createCustomerFromOrder(
                 $customer->setCompany($company);
             }
 
-            $gender = $order->getCustomerGender();
-            if ($gender) {
-                $customer->setSalutation($this->getSalutationFromGender($gender));
-            } else {
-                $customer->setSalutation($this->getSalutationFromPayment($order->getPayment()));
-            }
+            $customer->setSalutation(
+                $this->getSalutationFromPrefix($billingAddress->getPrefix())
+                ?? $this->getSalutationFromGender($order->getCustomerGender())
+                ?? $this->getSalutationFromPayment($order->getPayment())
+            );
+
             $birthDate = $this->getBirthdateFromPayment($order->getPayment());
             if ($birthDate) {
                 $customer->setBirthDate($birthDate);
@@ -500,7 +504,7 @@ private function updateGatewayAddressFromMagento(
     ): void {
         $street = $this->convertStreetLinesToString($magentoAddress->getStreet());
 
-        $gatewayAddress->setName($magentoAddress->getName());
+        $gatewayAddress->setName($magentoAddress->getFirstname() . ' ' . $magentoAddress->getLastname());
         $gatewayAddress->setCity($magentoAddress->getCity());
         $gatewayAddress->setCountry($magentoAddress->getCountryId());
         $gatewayAddress->setStreet($street);
@@ -571,6 +575,11 @@ public function updateGatewayCustomerFromOrder(OrderModel $order, Customer $gate
         $gatewayCustomer->setFirstname($billingAddress->getFirstname());
         $gatewayCustomer->setLastname($billingAddress->getLastname());
 
+        $gatewayCustomer->setSalutation(
+            $this->getSalutationFromPrefix($billingAddress->getPrefix())
+            ?? Salutations::UNKNOWN
+        );
+
         $gatewayCustomer->setCompany($billingAddress->getCompany());
         $gatewayCustomer->setEmail($billingAddress->getEmail());
 
@@ -659,9 +668,9 @@ private function validateGatewayAddressAgainstOrderAddress(
      *
      * @param Quote $quote
      *
-     * @return string
+     * @return ?string
      */
-    protected function getSalutationFromQuote(Quote $quote): string
+    protected function getSalutationFromQuote(Quote $quote): ?string
     {
         return $this->getSalutationFromGender($quote->getCustomer()->getGender());
     }
@@ -671,9 +680,9 @@ protected function getSalutationFromQuote(Quote $quote): string
      *
      * @param float|int $gender
      *
-     * @return string
+     * @return ?string
      */
-    protected function getSalutationFromGender($gender): string
+    protected function getSalutationFromGender($gender): ?string
     {
         switch ($gender) {
             case self::GENDER_MALE:
@@ -683,7 +692,7 @@ protected function getSalutationFromGender($gender): string
                 $salutation = Salutations::MRS;
                 break;
             default:
-                $salutation = Salutations::UNKNOWN;
+                $salutation = null;
         }
         return $salutation;
     }
@@ -700,6 +709,24 @@ protected function getSalutationFromPayment(InfoInterface $payment): ?string
         return $payment->getAdditionalInformation('salutation');
     }
 
+    /**
+     * @param ?string $prefix
+     *
+     * @return ?string
+     */
+    protected function getSalutationFromPrefix(?string $prefix): ?string
+    {
+        $prefix = strtolower(trim($prefix ?? ''));
+        if (str_starts_with($prefix, 'mrs') || str_starts_with($prefix, 'ms') || str_starts_with($prefix, 'mis')) {
+            return Salutations::MRS;
+        }
+        if (str_starts_with($prefix, 'mr')) {
+            return Salutations::MR;
+        }
+
+        return null;
+    }
+
     /**
      * Get Birthdate from Payment
      *
diff --git a/composer.json b/composer.json
index 2a4d80f..e14a6d3 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
     "name": "unzerdev/magento2",
     "description": "This extension for Magento 2 provides a direct integration of the Unzer payment types to your Magento 2 shop via the Unzer Payment API (PAPI).",
     "type": "magento2-module",
-    "version": "4.0.4",
+    "version": "4.0.5",
     "license": "Apache-2.0",
     "require": {
         "php": "~7.4.0|~8.1.0|~8.2.0|~8.3.0|~8.4.0",
diff --git a/etc/module.xml b/etc/module.xml
index f052ef0..0affbf9 100644
--- a/etc/module.xml
+++ b/etc/module.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
-    <module name="Unzer_PAPI" setup_version="4.0.4">
+    <module name="Unzer_PAPI" setup_version="4.0.5">
         <sequence>
             <module name="Magento_Checkout"/>
             <module name="Magento_Config" />
diff --git a/view/frontend/web/js/view/payment/method-renderer/basev2.js b/view/frontend/web/js/view/payment/method-renderer/basev2.js
index 5ad74d1..7c00f83 100644
--- a/view/frontend/web/js/view/payment/method-renderer/basev2.js
+++ b/view/frontend/web/js/view/payment/method-renderer/basev2.js
@@ -274,17 +274,33 @@ define(
                 const shipping = quote.shippingAddress();
 
                 const customerId = window.checkoutConfig?.customerData.id || '';
-                const uniqueCustomerId = `${customerId}_${email}_${shop}`;
+                const uniqueCustomerId = !quote.guestEmail && customerId ? `${customerId}_${email}_${shop}` : '';
 
                 if (unzerCustomerId) {
                     this.customer = unzerCustomerId;
                 }
 
+                const mapSalutation = (prefix) => {
+                    if (!prefix) return "unknown";
+
+                    const normalized = prefix.toLowerCase().trim();
+
+                    if (normalized.startsWith('mrs') || normalized.startsWith('ms') || normalized.startsWith('mis')) {
+                        return 'mrs';
+                    }
+                    if (normalized.startsWith('mr')) {
+                        return 'mr';
+                    }
+
+                    return "unknown";
+                };
+
                 const customer = {
                     id: unzerCustomerId || '',
                     customerId: uniqueCustomerId,
                     firstname: billing ? billing.firstname : '',
                     lastname: billing ? billing.lastname : '',
+                    salutation: billing ? mapSalutation(billing.prefix) : 'unknown',
                     email: email,
                     ...(customerData?.dob ? {birthDate: customerData.dob.split('T')[0]} : {}),
                     billingAddress: billing ? {