public function markAsUsed($sOrderId, $sUserId, $dDiscount)
    {
        //saving oxreserved field
        if ($this->oxvouchers__oxid->value) {
            $this->oxvouchers__oxorderid->setValue($sOrderId);
            $this->oxvouchers__oxuserid->setValue($sUserId);
            $this->oxvouchers__oxdiscount->setValue($dDiscount);
            $this->oxvouchers__oxdateused->setValue(date("Y-m-d", \OxidEsales\Eshop\Core\Registry::getUtilsDate()->getTime()));
            $this->save();
        }
    }