The account is buy and hold account. So I rarely check.
That's the worst ever thing one could do, and the worst thing that could happen actually happened in your case. I'm surprised no one pointed that out yet.
Exchanges in no shape or form are wallets or accounts you can store your funds in for a longer period of time. These platforms are solely meant for trading purposes, where if you are done with trading, you withdraw all your funds back to your own wallet (one you as sole entity has access to).
I do feel bad for you though, it's the lack of knowledge and understanding of how fundamentally unsafe exchanges really are (regardless of how "regulated" they are) that made you lose out big time.
Get yourself a hardware wallet;
https://shop.trezor.io/
https://www.ledger.com/
For obvious reasons only buy from the original web shops and not some third party sites.
