try this:
PHP Code:
<?php
$site_link = 'http://refer.ccbill.com/cgi-bin/clicks.cgi?CA=933495-0000&PA=1632535&HTML=http://www.britishslags.com/';
if(isset($_GET['ccbill_id'])){
$site_link = 'http://refer.ccbill.com/cgi-bin/clicks.cgi?CA=933495-0000&PA=' . $_GET['ccbill_id'] . '&HTML=http://www.britishslags.com/';
}
?>