I had this issue. Here is where you should go for the best possible information:
http://itracki.com/tutorial-scratched-off-your-itunes-gift-card-code/
Here's what NOT to do
Attempt to get help at:
http://www.apple.com/support/itunes/
or call Apple at 800-MYAPPLE
You just get endlessly shuffled around. At one point I was asked for my Apple ID on one of these pages and got an "INVALID LANGUAGE CODE" after entering my UID and password. It was just absurd!
I eventually was able to get an email address for this issue. I sent an email and received a confirmation that I would most likely here something in 24 hours. 24 hours came and went, no answer. I am generally a big supporter of everything Apple, but this is a bad issue for Apple, I wish they would handle this better.