LOL, I just made Microsft spend 50 bucks on me!
I was on the phone for about a good 30 minutes with a games for windows live representative, and in the end, he ended up purchasing a copy of Batman Arkham City for me from the games for windows marketplace to replace the copy I had.
I can't believe he had to go to such lengths, but I appreciated it. He used remote connection so he could verify that I really did own the game, and once he did that, he just bought me another product code and now everything is as it should be..