It seems they think you will not be happy with any solution they had offered you previously.
What solution did they offer me earlier?
You flooded their customer support with messages before getting locked out of your account. Surely they must have given you some options during that time. You never mentioned what they said in this period, but I would imagine your best option was exchanging the MONA for BTC, and then withdrawing your BTC.
If they reinstated your account, you would still be unhappy about not being able to withdraw the MONA, correct? It seems like they tried their best to explain the situation to you and that wasn't good enough.
The best chances you have of getting your money back now is taking them to court.
I have repeated this many times already, that they did not propose any solutions, all they suggested was to go and solve the problem with the developer on their own. And the rest of the correspondence, I have already shown.
Who should I sue? The site has no official representatives and a registered company.
They just stole my money and are not going to return anything