Poor business practice and unprofessional

I signed up for Gym Company 2 or 3 years ago at Maponya Mall with those guys that always make you feel uncomfortable in the mall from Gym Company then a few days later, I decided that I don't want the contract anymore. I went to their offices to tell them and they told me that I was supposed to have come within 7 days of signing and the day I went was on the 8th day. So, they refused to cancel it even though I didn't use their services and they debited 3 times but I reversed the payments then they stopped.

Last year in October I signed new contract with them and they debited and I used their services. This year in July, they called me telling me that I have a pending contract which costs R8000 and I must come to their offices to close it by paying R400. I said to them, I never got any calls or letters saying that I need to settle it because I thought that the contract was canceled. So, I didn't go pay off the contract then August they didn't debit and September then I phoned them to find out. They said that they stopped debiting because I need to settle that contract first the continue with the new one.

What I don't understand is that, couldn't they see when they activated my new contract that I have a pending one? Why activate a new contract when there is an old one to be settled and only see it 9 months later? Now, I have a debt that they caused by not debiting.