Yes, yobit is completely unresponsive in their customer support now.
Most people will see delays of up to months or even years before their customer support tickets are responded to. You just seem to be another victim of that. Consider this money gone for now, but keep following up with yobit until they respond. Also, learn the lesson and don't use yobit again, please.
yobit has a bad habit to lock wallets for months making withdrawals to be a real game there. I don't trust this exchange any longer.