XML invalid tags

XML invalid tags

what i should do to prevent invalid XML tags in the custom getaway's
callback function?
$h = fopen("banks/Mybank/log.txt", 'a');
fwrite($h, 'ConfirmRequest:
'.print_r($_REQUEST['ConfirmRequest'],true)."\n");
fclose($h);
the output is:
ConfirmRequest: <ConfirmRequest><TransactionId> Cool Attitude
#89</TransactionId><PaymentId>327600020200</PaymentId><PaymentDate>02.10.2013
23:41:26</PaymentDate><Amount>7000</Amount><CardType>VISA!472291******9871</CardType><Status>N</Status><Reason>Declined
by merchant</Reason></ConfirmRequest>
the result is same on
$_REQUEST['ConfirmRequest'];
and
$this->resuest->request['ConfirmRequest'];