This is what I settled on as a solution, and it looks like it's working.
I used the following hidden fields at the beginning of the form
<input type="hidden" name="Installment" id="Installment" value=""/>
<input type="hidden" name="Periodicity" id="Periodicity" value="Month" />
For the options that are one-time payments, the input tag was like this (note the onclick event):<input type="hidden" name="Periodicity" id="Periodicity" value="Month" />
<input type="radio" name="UnitPrice1" id="UnitPrice1" value="240" onclick="javascript:document.getElementById('Insta llment').value=''"/>
for the options that are multiple payments:
<input type="radio" name="UnitPrice1" id="UnitPrice1" value="20" onclick="javascript:document.getElementById('Insta llment').value='12'"/>
This way, the default is no installments, so if javascript is disabled on the browser, they won't be overcharged. I can probably set something up to flag transactions with a multi payment option and without an installment value. If the user changes their mind (clicks on a multi-payment option and then changes it to a single payment option), the value gets set back to nothing.
BTW, in the process, I discovered that if a transaction fails due to an invalid credit card (in this case I was one character short on the test credit card number)- there is no error returned to indicate that this is the problem.
So there ya go!

Originally posted by CarolinaTigerRescue
View Post
Leave a comment: