THEY DONT WANT TO CANCEL MY MEMBERSHIP

I was at the mall the people from gym company approached me and said that I should come and see their September special and I refused and they followed me to the car and said that I should show them my card and and give them my ID number so they can check if I qualify to be a member and I did as they said ..then later after 3 months they deducted from my account then I stopped it from deducting, Few months later I receive an email saying that I owe them R1200 which I have never agreed to work with them .there's no contract that I have signed ...can they cancel this membership because I have never set my foot in their gym. I sent them an email to cancel it still they don't want to.