I saw the CoD story on Reddit yesterday, but to hear it happened with another game is shocking. Black Ops 2 should be available to download from Steam if you've activated the product key, so it's just a matter of waiting longer to play the game. The steps, once you've activated the key:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam...
Follow the onscreen instructions to complete the process.