And he's saying why the hell didn't Blizzard just deactivate your account? It's ridiculous that they would continue to let you play and then send that to collections when all they had to do was deactivate your account because you didn't pay. If I'm not mistaken you get charged up front, at the start of the month, not the end after you've been playing all month.
It's actually kind of unbelievable to be honest. I've had similar situations where my CC expired and I forgot to change it, and the game I was subscribing to just deactivated my account when it was declined.