Originally Posted by redwhiteandblue

CCBill doesn't pass the parameters through so the only way you can possibly get them is by looking at the referrer string ($_SERVER["http_referer"]) but that would be terribly unreliable since whether the referrer string is present depends on many things including the level of privacy set in the user's browser.

You would have to take a different approach and get affiliates to send traffic to a landing page on your site which captures the params, constructs the CCBill URL with them and then redirects to it, which will then redirect the user back to your home page.