Dischem-gift voucher

I received a gift voucher for my baby shower. The gift voucher card has been lost/******. Even with the proof of purchase, that has the card/voucher number on they will not let me use the voucher. They can block the voucher with the voucher number but will not let you use your gift money on the voucher, which I'm sure they can verify with the voucher number. It's really disappointing that they are not willing to help and keep the money even though you have a proof of purchase. Very disappointing.