All I can say is.. when I place a trade and then remove then replace over a 24 hour period and INSTANTLY their appears a price that blocks my trade then when I remove it the exact same price blocks the next trade... acting as it was machine generated...
Maybe what you encountered was a trading bot. There are traders who use a bot that will automatically execute trades for them and as I experienced it works like that - instantly placing and cancelling orders (this applies in other exchanges to).
I didn't encounter any problem with Yobit, but considering all the problems/accusations that other users have experienced, especially with their support, it might be better to use other exchange.