Won a giveaway....

All you can do is mark the game as "Not received" in 7 days and move on.

mark as not received, it's not your problem, the creator of the giveaway can be lying and activated the game on his own account
maybe i'm too paranoid :s

Wait a week, mark as not received.

Also, the hell there's nothing Indiegala support can do. They are supposed to provide a working key, if they don't they need to provide a replacement, if they don't have one then it's their duty to request one from the publisher/developer. There's plenty they can do. If they've gone through all that and still haven't been able to provide what the customer paid for, then they should offer another product in its place as a customer service gesture. Whoever's giveaway you won should not have stopped bugging Indiegala support until they gave them what they paid for.