What is written on the TOS is irrelevant: they cant keep your money without presenting a very good reason. Suspending and terminating an account is one thing. Keeping the balance is another. You wrote years ago. You are talking about real bitcoins or just fractions of 1 bitcoin? If you have there some bitcoins you will have reason and ground to move this to a finish court. But you can try first finish financial regulators.
https://www.finanssivalvonta.fi/en
As another member posted you also should post evidence hiding any sensitive information.