My friend used this exchange a few times, and he also had delays of up to several days. I know that most of the coins on this exchange just dead! I do not advise there to trade!
Yobit exchange is not a scam and as my experience in yobit exchange, my deposit and withdrawal are very fine, sometimes it delay but its only an hour. But before doing trade in yobit, better to do a search if yobit is scam or not. If you experience any problem, just do to create a ticket and then wait for the support to response.