Cancellation of contract

I wanted to cancel my contract with sports and fitness 4 years ago. When I asked to cancel I was told that I was not allowed to cancel my contract and that I had to finish paying my instalments until my contract ends.<br> I then told them if they do not cancel my contract I will then stop paying. And so I did.<br> Now they have handed me over with a default amount of R5609.00. In what lifetime are you not allowed to cancel a contract??????