What asking him kindly?
He's got them now, if a bitcoin exchnage can't get a user to give back 511BTC that was accidently sent to them I doubt you'll have much luck.
There are many ways that I could possibly recover my bitcoins but the fact is that I need to track down the thief first anyway so there really is no point to going into detail about it here. Please, if you don't have anything to contribute to my original question then don't post in this thread.