public function execute()
    {
        parent::execute();
        $xml = new DOMDocument();
        $hpsTransaction = $xml->createElement('hps:Transaction');
        $hpsManageTokens = $xml->createElement('hps:ManageTokens');

        $hpsManageTokens->appendChild($xml->createElement('hps:TokenValue', trim((string)$this->token)));

        $hpsTokenActions = $xml->createElement('hps:TokenActions');
        $hpsSet = $xml->createElement('hps:Set');
        $hpsAttribute = $xml->createElement('hps:Attribute');

        $hpsAttribute->appendChild($xml->createElement('hps:Name', 'ExpMonth'));
        $hpsAttribute->appendChild($xml->createElement('hps:Value', (string)sprintf("%'.02d", (int)$this->expMonth)));

        $hpsSet->appendChild($hpsAttribute);

        $hpsAttribute = $xml->createElement('hps:Attribute');

        $hpsAttribute->appendChild($xml->createElement('hps:Name', 'ExpYear'));
        $hpsAttribute->appendChild($xml->createElement('hps:Value', (string)$this->expYear));

        $hpsSet->appendChild($hpsAttribute);

        $hpsTokenActions->appendChild($hpsSet);

        $hpsManageTokens->appendChild($hpsTokenActions);

        $hpsTransaction->appendChild($hpsManageTokens);
        $trans = $this->service->_submitTransaction($hpsTransaction, 'ManageTokens', null);

        $trans->responseCode = '00';
        $trans->responseText = '';

        return $trans;
    }