I doubt that Yobit will help you with their almost inexistent support who only care about profting with shitcoins.
Anyways, if you want to try something, send them a support ticket. They are literally the only ones who can help you.
[1]
https://yobit.net/en/support/Other than that you can also try hassling them on social media. These companies don't like bad publicity so they'll be more likely to look into a support ticket if it's getting a lot of attention.
The problem here is that it is actually your mistake and under their terms of service they are within their rights not to sort it out. It may not be morally right but that's a different issue. If it doesn't get resolved just learn a lesson from it and be more careful to check if a service accepts smart contracts before sending them in future.
