I know I have said this many times, But threaten them for lawsuit. It always makes them shit bricks and give you your money back.
Threatening Gox is really ineffective from my experience. These threats are certainly common and Gox support is conditioned to ignore them. Alternatively, filing an actual lawsuit will go directly to legal, bypassing support, and may actually accomplish something.
I know right? Just tell your lawyer proof that the are your funds and they will have to give them back. Because if those werent your funds, You can go to jail, and I think a hacker wouldnt go to court if he says he was the rightful owner.