Someone I know wrote this on his face book 7 hrs ago:
To everyone with HMV vouchers that won't be valid. Stop whinging about it and just walk into the shop, take items which amount to how much your Voucher is worth, walk out... If questioned, start acting like a chimpanzee and throw the voucher on the floor making monkey noises and jump out of the shop. The confusion will help.
Guess he knows him..