I have account on YoBit.net from time I was participated in their signature campaign and I also promote my ref link in signature so I get some nice number of referrals which make my some BTC there.I just check and all balance is there,so far I have no problem with them.Before they send me e-mail for log in verification,but this is not the case anymore.

Is it possible that you and some others are victims of phishing or your log in data was exposed in any way?