function user_has_gv_account($c_id) {
    global $db;
    $gv_result = $db->Execute("select amount from " . TABLE_COUPON_GV_CUSTOMER . " where customer_id = '" . (int)$c_id . "'");
    if ($gv_result->RecordCount() > 0) {
      return $gv_result->fields['amount'];
    }
    return 0; // use 0 because 'false' was preventing checkout_payment from continuing
  }