Yobit, their support is very very slow (your response even not to get solved for a long time if you have some problems on there). Beside of that, their volume also looks like faked by pump and dump. Better to stay away from them
Yobit does not have supports for their users, not slow-supports. I think there is no support from Yobit to their users. However, it is likely incorrect to judge Yobit is a scam exchange. They are a shady, no-support exchange, but has not still been enough to call them as scam one.