Fight club refuses to treat me decently

I joined the centurion fight club 3 months ago. My membership is R649 a month. Just more than a month ago my knee became swollen and very sore. Oh have been in pain and limping. My Dr advised me to stop boxing and gave me a letter for Fight club. After one month of freezing my payments I asked to cancel the gym membership due to this medical issue. The fight club advised me to pay R5300 !!!! This does not make sense at all. When I questioned this I was ignored all together. Cancellation fee can not be similar to what I would have paid in anyway......how can that be? Fight club is *****