diff --git a/LidlConnect/api/credit.py b/LidlConnect/api/credit.py
new file mode 100644
index 0000000..3c37755
--- /dev/null
+++ b/LidlConnect/api/credit.py
@@ -0,0 +1,58 @@
+"""Credit-related API functionality for Lidl Connect."""
+
+class CreditMixin:
+    """Credit methods for Lidl Connect API."""
+    
+    CREDIT_URL = "https://selfcare.lidl-connect.at/credit/code"
+    
+    def credit_topup(self, code: str) -> bool:
+        """
+        Top up credit using a voucher code.
+        
+        Args:
+            code: The voucher code to redeem
+            
+        Returns:
+            True if the top up was successful, False otherwise.
+        """
+        if not self.logged_in or not self.csrf_token:
+            raise ValueError("Not logged in or missing CSRF token")
+        
+        headers = {
+            "Accept": "application/json",
+            "Content-Type": "application/json;charset=UTF-8",
+            "X-Requested-With": "XMLHttpRequest",
+            "Origin": "https://selfcare.lidl-connect.at",
+            "Referer": self.DASHBOARD_URL,
+            "X-CSRF-TOKEN": self.csrf_token,
+            "X-SELF-CARE": "1",
+        }
+        
+        phone_number = self.phone_number
+        if not phone_number:
+            raise ValueError("Phone number not available")
+        
+        payload = {
+            "phoneNumber": phone_number,
+            "code": {
+                "label": "credit_top_up.bon",
+                "code_fields": 1,
+                "code_field_length": 16,
+                "code_validation": "^([a-zA-Z0-9]+)$",
+                "active": True,
+                "api_type": "VOUCHER_WITH_ACTIVATION_NUMBER",
+                "code": code
+            },
+            "userId": self.user_id,
+            "endpointId": self.endpoint_id
+        }
+        
+        r = self.session.post(self.CREDIT_URL, headers=headers, json=payload)
+        
+        if r.status_code != 200:
+            return False
+        
+        if hasattr(self._get_user_data, 'cache'):
+            self._get_user_data.cache.clear()
+        
+        return True
\ No newline at end of file
diff --git a/LidlConnect/client.py b/LidlConnect/client.py
index cea6d03..6bc566a 100644
--- a/LidlConnect/client.py
+++ b/LidlConnect/client.py
@@ -11,8 +11,9 @@ from .api.utils import ApiMixin
 from .api.user import UserDataMixin
 from .api.tariffs import TariffsMixin
 from .api.invoices import InvoicesMixin
+from .api.credit import CreditMixin
 
-class LidlConnect(AuthMixin, ExtractorMixin, UsageMixin, ApiMixin, UserDataMixin, TariffsMixin, InvoicesMixin):
+class LidlConnect(AuthMixin, ExtractorMixin, UsageMixin, ApiMixin, UserDataMixin, TariffsMixin, InvoicesMixin, CreditMixin):
     """Client for interacting with Lidl Connect Self-Care portal."""
     
     DASHBOARD_URL = "https://selfcare.lidl-connect.at/customer/dashboard/"
diff --git a/LidlConnect/helpers.py b/LidlConnect/helpers.py
index e0aa745..3cfe34a 100644
--- a/LidlConnect/helpers.py
+++ b/LidlConnect/helpers.py
@@ -30,5 +30,6 @@ def ttl_cache(ttl_seconds=30):
             cache[key] = (result, now)
             return result
         
+        wrapper.cache = cache
         return wrapper
     return decorator
\ No newline at end of file