HT1574: Redeeming iTunes Gift Cards and content codesLearn about Redeeming iTunes Gift Cards and content codes
Currently Being ModeratedSep 19, 2012 6:22 PM (in response to slee27)
someone else redeemed it or your putting the code in wrong, contact itunes support about this at https://expresslane.apple.com/ they should be able to do something about it if you can prove you own the gift card
Currently Being ModeratedFeb 25, 2013 2:57 PM (in response to slee27)
Same problem discussed here (as well as a link to a video of the problem happening). https://discussions.apple.com/thread/3783681?start=0&tstart=0
It is a valid and important problem but it would seem Apple are deciding to ignore it. I can understand them asking to see a receipt but as you have said, when buying them as gifts for people it is highly unlikely that you will keep said receipt. You automatically expect the card to work!!
Kick up a fuss with your local Consumer Protection organisation. Get in touch with your local press and explain the problem to them.