Mix Telematics - no feedback or assistance

Mic Telematics sold me a tracking device for my Toyota Fortuner in December 2018 with a lower monthly cost than my existing tracking system (which expired in December). I traded my vehicle in May 2019 and bought a new system through Toyota. When I tried to cancel the tracker at Mix Telematics, they informed me that I must first pay a cancellation fee of +-R 900. I told them that they did not inform me about this penalty when the product was sold to me over the telephone. I requested a copy of the recording and told them that if it was mentioned to me, I will pay the cancellation fee and apologize. But it has been almost 3 months now and no one in coming back to me. They are still taking R 120 pm, but I am paying for something that I cannot use. I have been considering a trade in since November 2018, so if I knew I had to pay this for 2 or 3 years, I would not have taken the system. It is almost impossible to get hold of them and they ignore e-mail requests.