Refused to cancel contract

I joined the gym in 2013. The sales rep told me the contract was for 6 months and it was convenient and cheap for me because I was an intern hired on a 6 months contract. I got the shock of my life when I wanted to cancel my membership and was told the contract was for 36 months. A contract I wouldn't have signed since my work contract would expire in a shot space of time. The lady from finance told me that I should get someone to take over my account or pay 50% of the remaining term of contract. These people have been deducting money from my account since then. They provide poor service and don't deliver on their promises. I paid R100 for a membership card that I never received and they kept saying the cards would come for the 4-5 months that I spent going there.