[Asiaplay]

Ok - so QT didn't change the code for One page checkout (as it is not an X-Cart standard - not helpful really, as if it doesn't work at checkout, is a useless mod to you)...
I guess the outcome on this depends on how you wrote the specification then (as they are very word for word on these things).
But should be an easy fix if they want to help... good luck!

Cheers - Asiaplay

PS: feel free to ask via PM for contact I mentioned, if you still need alternative programmer to fix it after discussions are done...