As Jtank said, we can't/won't do anything without concrete proof to back up your claims. If you want to make sure you have proof in future it would be easy to type /bets and /decapprize if you suspect someone is pinging/quiting mid match. Typing them and screening the info given would be a good tip when you get a big decapprize and a decent number of bets as a precautionary anyway.
That would help your case immensely in future.