their system has many problems, i also had trouble singing in my account a while back. you either have to wait, restart your router, change your IP and try signing in again.
or try contacting support and keep your fingers crossed that they answer you within less than a week.
I contacted the support and they replied within an hour saying, you would be able to log in after 15 minutes and here it is still I'm not being able to get in. Seems like I need to try resetting my Ip.
No problems here. I am using yobit at the moment.
I would recommend you reset your router and delete the cache and cookies of your browser. Which browser are you using? DId you log in from different locations recently? Might be a problem of logging in from different IPs.