diff --git a/templates/index.html b/templates/index.html
index 042b938..96cb586 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -322,9 +322,13 @@
                    </a>`;
         }
 
-        function createCustomerLink(customerNumber) {
-            if (!customerNumber) return 'N/A';
-            return `<a href="medisw:openkkbefe/P${customerNumber}?NetGrp=4" class="customer-link">${customerNumber}</a>`;
+        function adjustCustomerNumber(number) {
+            return number - 12000;
+        }
+
+        function createCustomerLink(number) {
+            const adjustedNumber = adjustCustomerNumber(number);
+            return `<a href="medisw:${adjustedNumber}" class="customer-link">${adjustedNumber}</a>`;
         }
 
         function showCopyFeedback() {