I don't know much about I-tunes, i prefer old records to this new technology XD But have toi tried ringing their customer service line, explaining the situation and possibly getting them to tell toi the last few numbers ou even possibly giving toi a refund? ou toi could take it back to the boutique and see if they would swap it back for you?
I really can't help toi there. I've never had that trouble. It's pretty dang hard to scratch the numbers off the back of that thing. =) But I guess it can happen. I'd try contacting customer service. If that doesn't work, I really don't know what to suggest. Sorry.