Is there a way to get them to respond?
I'm sorry that you had to go through this dreadful experience. It's really a pain in the arse when you have a problem with the operation of the site, and they just flat out ignore all of your requests. But hey, that's yobit in a nutshell. I think you knew the risks when you were depositing money into yobit, and unfortunately, that risk did not pay off.
Even if they do respond to your ticket, it's impossible for them to refund your EOS withdrawal because technically, you agreed with the terms and the amount of fee you would be paying when you submitted the withdrawal.
However, you should keep creating new tickets if they are flat out ignoring your old ones about your ZCash withdrawal - you deserve to get it. But there is really no easy way to get them responsive, unfortunately. Otherwise, they wouldn't have as bad a reputation as they do.