they are not a legal entity that should do that.
Have you read their TOS page?
I am sure they can claim you agreed with anything written in their terms when you used their exchange:
https://fixedfloat.com/terms-of-serviceThis is not the first time I hear complains about Fixedfloat exchange, but they are known to have very low rating and they could even ask for kyc with personal ID verification to get your coins back.