I have an iTunes Gift Card and the numbers needed to redeem it scratched off while i was taking off the sticker, is there anything I can do to return it?

I just bought an iTunes card at a convienience store (shell) last night because I wanted to buy some music. I took a coin and started to scratch off the sticker covering the code. The code is needed to redeem the card, but the stupid numbers actually scratched off with the sticker and I wasnt even scratching hard!! Is there anything I can do to somehow return the card to the store, or somehow get my money back?. I have a feeling they are just going to say that theres no proof on wheither I used it or not. I can see the first couple numbers, then they are all scratched and un-legible. HELP?