Dynamic Forms

Hi, me again I have a form, which can either display debit order details, or credit card details. When a user opens the page, he gets a dropdown menu, which gives him the options. If he selects debit order, the debit order form gets displayed, this is all done with if statements, no jscript. This works fine, but with the mail part I have a problem. How would I be able to tell my mail function what to mail, and what not to? When a user clicks on the debit option, it must only email the debit form's details, as the forms differ quite a bit. I tried doing it with a case statement, but with no luck. Can anyone please help me with this? Thanx Rudi Ahlers