I have been trying to sort out my account for months

I have been trying to sort out my account for months. I had a device on my previous car but when I bought a new car and called cartrack no one said anything about removing and reinstalling the device from the old car to new car. Months later I am being billed for 2 devices I contact them and they tell me they will remove the device from the old car and bill me an extra R600 and I still agree and it is taken by cartrack. A month later I am still being billed for 2 devices even though I only have one device and they took the other one. The only way I could get their attention is by reversing the debit order, anyway 4 months later I am still waiting on the account to be sorted out.