Workaround for cc reward voucher?

This is a supplementary question to my earlier on on the cc reward voucher expiry date.

I've read on some other forums people saying that you can book flights using the voucher and then move the dates back in order to get around the expiry date. I just wondered if anyone here had done this and if there were any risks if they refuse to do it (presuming that you could just cancel and pay the fee?) Thanks

Can anyone help? I've read people saying that they tried it and the person on the call knew that it wasn't supposed to do it but did it anyway!

It used to be possible to do this but that hasn't been the case for a long time. I would be surprised if anyone got an agent to do it.
If you move/change a booking they tend to refund all miles and vouchers back to you account then rebook it. They then check the date on the voucher. The agents are now sticklers for process and do not tend to bend any rules as I think they get into a lot of trouble now. They are definitely less flexible and the system now works in virgins favour rather than ours.
But I would be happy to be proved wrong.