Exchanges have their own terms and conditions which you agreed to while creating your account, probably you didn't even read anything in TOS, just clicked agree and created it that's why it comes to your knowledge only after it happens.
The reputation of the exchange is not great either and the coin you're talking about is traded on any other exchange or just on HitBTC?
You're wrong, sir!
I read them carefully and I know exactly what I accepted.
There were no such taxes, but they were introduced later "illegally".
Not informing about changes is illegal. In 11.3 they guarantee to do so and by the way they violate the law in countries where they offer their service. That's how a thieve justifies his theft.