Charging me settlement amount because they extended my contract with 5 months blaming covid for it

Due to covid I decided that I still don't want to go back to gym even though they are allowed to be open now. I was told that because they froze everyone's accounts during lockdown that they added 5 months to my contract which means I must pay a settlement amount of R1800 to cancel my contract. I did not ask for covid to happen so should not be held accountable for not being allowed to go to gym and having my contract extended!!! Please sort this out ASAP.