1: Limited Edition is no longer sold. If this is the way they identified it as a 'pre-owned' game, then ignore #2
2: How would they know it is a pre-owned game?
3: $80 is extremely expensive for a pre-owned game. You can easily buy it for half the price completely new.
4: Just doesn't make sense.. how could you have bought a copy not seeing it was preowned.
If you end up being stuck with the invalid code, and EBGames is shitty enough to not give you a replacement or refund, i'll help you out more. It was a bit stupid of you to throw away the receipt (look in the trash?), but if all else fails, dispute the payment with your credit card company if you paid with a credit card. Let me know if any of this works ^^.