Bad service provider

I joined auto and general commercial insurance in February this year , while I was joining I was told that auto and general will fit their own tracking device in order to calculate kilometers driven monthly and that I won't be responsible for the payment, I agreed .July I have canceled the insurance .to my surprise 1 September nestar tracker debit me R79 without my authorization. I called them today to ask why are you debiting my account , the consultant said I entered into 3 years contract with them when I joined auto and general and I further explained that I had my tracking device at that time ,auto and general said is their own baby to pay the device .

I'm not happy with nestar and auto and general ,now I must be responsible for a tracking device that I never authorized for it .I tried reversing my debit order and it cannot be reversed .

Nestar and auto and general services are ****, now they are forcing me to continue to pay for something I never initiated .