Hummm, I wonder the same. Would you accept if in your work they pay your salary with gift vouchers instead???
Darling gift vouchers are a gesture of appreciation for the time that you spend with the lady, not a payment method, it's extra, it's a present.
I can't believe that this needs to be addressed.
When in doubt of what to do in certain situations think first how would you feel if was with you, how would you feel if your company instead of your salary hands over a few gift vouchers for boots, M&S, BT, amazon etc, would you be able to pay your mortgage? Your credit card? I know I wouldn't.