public function execute()
    {
        parent::execute();

        $xml = new DOMDocument();
        $hpsTransaction = $xml->createElement('hps:Transaction');
        $hpsPosCreditCPCEdit = $xml->createElement('hps:CreditCPCEdit');
        $hpsPosCreditCPCEdit->appendChild($xml->createElement('hps:GatewayTxnId', $this->transactionId));
        $hpsPosCreditCPCEdit->appendChild($this->service->_hydrateCPCData($this->cpcData, $xml));
        $hpsTransaction->appendChild($hpsPosCreditCPCEdit);

        return $this->service->_submitTransaction($hpsTransaction, 'CreditCPCEdit');
    }