try to disable downgrades

zimbraSingle.php

@@ -392,6 +392,18 @@ function zimbraSingle_CreateAccount($params) {
     $attrs['zimbraCOSId'] = $cosID;
 	$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;
+    $results = localAPI('UpdateClientProduct', ['configoptions' => base64_encode(serialize($params['configoptions']))]);
+    logModuleCall(
+        'zimbrasingle',
+        __FUNCTION__,
+        $params['configoptions'],
+        'Debug',
+        $$results
+    );
     $attrs['zimbraMailQuota'] = ($baseQuota + $addonQuota) * 1073741824;
     $zimbraID = $apiAccountManager->createAccount($params['username'], $params['password'], $attrs);
     if(is_a($zimbraID, 'Exception')) {