I doubt legal action would work because yobit's terms and conditions cover it from any user mistakes. A long wait for a reply to a support ticket is the OPs best hope.
https://yobit.net/en/rules/Visiting the Website means that the User accepts the given Agreement and all the terms and conditions stated below. The User is obliged to fulfill all the local legal responsibilities in the country he is resident of and to take complete responsibility in case of their violation. User undertakes complete responsibility for taking decisions on trade transaction fulfillment. The Stock Exchange is not liable for possible losses caused by User's ineffective funds management.
Those terms and conditions clearly state that Yobit is not liable for any possible losses, nothing is lost here, it is sitting in my BCC address (unless they have already taken it out and spent it which is more likely the case) and it is recoverable. If it is recoverable, then how can it be lost?
Had their terms said "If you make a mistake, and we can profit from it, we will do so without giving a fuck about our customers" then you would have a valid point, but the funds are not lost, just sitting in the wrong wallet, easily rectified by using the private keys to recover the BTC but they are not doing so thus far or if they have done so, they have kept the lot for themselves.
Either way, not one single reply to 10 support tickets, what does that tell you? There is not even an attempted reply of Plausible deniability from them.