I have tried to contact YoBit support and PM for a long time. Can someone from YoBit please contact me...
Blacksmith is the admin of YoBit. He is offline all the time.

I have a problem yesterday when I wanted to exchange my EPC to BTC but he didn't reply me till now!

I think he is on holiday now. Lets wait for him to come back.
but you noticed that the coin you're trying to sell is impossible to complete because have a sell wall of 9btc? Did you even checked if there was a buy order before creating a sell one?
If bit coin price goes down will you update campaign rates

?
For what i know the rates never changed and who knows when got changed last time, i think that the fact that are stable is a good point even if i must admit i don't know how the other signature campaigns react to bitcoin price changes