They have scammed me too. I had 1.1 milliion FJC sat in there for a while and tried to withdraw it to a valid address two weeks ago. It never arrived, instead sitting at 0/20 confirmations the whole time. Now, perhaps for complaining, they have banned my account.
There is absolutely NO support at Yobit, so if this happens to you, your coins are GONE. There are reports that Yobit never updated their FJC wallet to the new chain, and this is the case also for many other coins at Yobit.
Stay away from this exchange. It is a rudderless ship, and it looks like they are harvesting people's withdrawals, probably with the intention of disappearing forever very much like Cryptsy did a few years ago.
AVOID YOBIT. IT IS A SCAM.