try to use AdminServicesTabFieldsSave

zimbraSingle.php

@@ -393,18 +393,7 @@ function zimbraSingle_CreateAccount($params) {
 	$baseQuota = $params['configoption2'] ? $params['configoption2'] : 1;
     $addonQuota = $params['configoptions']['addonQuota'] ? $params['configoptions']['addonQuota'] : 0;
     $newAddQuota = $params['configoptions']['newAddQuota'] ? $params['configoptions']['newAddQuota'] : 0;
-    $addonQuota = $addonQuota + $newAddQuota;
-    $params['configoptions']['addonQuota'] = $addonQuota;
-    $params['configoptions']['newAddQuota'] = 0;
-    $results = localAPI('UpdateClientProduct', [ 'serviceid' => $params['serviceid'], 'configoptions' => base64_encode(serialize($params['configoptions']))]);
-    logModuleCall(
-        'zimbrasingle',
-        __FUNCTION__,
-        $params,
-        'Debug',
-        $results
-    );
-    $attrs['zimbraMailQuota'] = ($baseQuota + $addonQuota) * 1073741824;
+    $attrs['zimbraMailQuota'] = ($baseQuota + $addonQuota + $newAddQuota) * 1073741824;
     $zimbraID = $apiAccountManager->createAccount($params['username'], $params['password'], $attrs);
     if(is_a($zimbraID, 'Exception')) {
         logModuleCall(
@@ -801,3 +790,16 @@ function zimbraSingle_ServiceSingleSignOn($params) {
         'redirectTo' => $preauthURL,
     );
 }
+
+function zimbraSingle_AdminServicesTabFieldsSave($params) {
+    $params['configoptions']['addonQuota'] = $params['configoptions']['addonQuota']  + $params['configoptions']['newAddQuota'] ;
+    $params['configoptions']['newAddQuota'] = 0;
+    $results = localAPI('UpdateClientProduct', [ 'serviceid' => $params['serviceid'], 'configoptions' => base64_encode(serialize($params['configoptions']))]);
+    logModuleCall(
+        'zimbrasingle',
+        __FUNCTION__,
+        $params,
+        'Debug',
+        $results
+    );
+}