So after a few emails with the oh so great support I now know following:
"Your account was blocked due to fraudulent behaviour and we can do nothing with it."
According to their terms of services they can block any user that appears to have "fraudulent behaviour". Well this is understandable if somebody cheats, but I didn't, and they can't deliver absolutely no proof. Seems like one big scam, as soon as somebody wins a certain amount they just call it fraudulent behaviour.
As to my account having no funds anymore: "Funds are in your FairProof account only within 30 days after the last activity."
WTF? So by not letting me withdraw I would have had to basically keep gambling?
This just seems like one big joke. Sadly it isn't. The support (that of course doesn't even have a name) is being dead serious and somehow thinks this is a good way to do business.
Sad really, I liked the site, but I advise everybody to stop using the site.
Well, at least if you're planning to win, they only block users that win.