Tracker problem

In June I sold my car and before I did I called cartracker to inform them so they can remove the device and they didn't come and on the day I sold the car to we buy cars I called them letting them know they have two days to remove the device and gave them contact details and it's a must they remove it within two days so they can put it up for sale... They made me pay fee for removal and I did... I bought a new car and told them so they can fit the tracker to the new car only to find out they didn't remove the first one and it's in cape Town to its new owner of which I don't know also, I asked them how cause I gave them time and place and they said they will get back to me... End of August they debit again I was shocked cause I'm still waiting for them to get back to me about the first one and I called them to be told they can't find the vehicle I have to make payment for it I got so upset that I dropped the call end of October I decided to reverse the money cause I can't be paying for a device that's not installed... They started to blow my phone cause of that and I asked them how am I paying for something that I don't have and they asked to fit the device on the new car I refused and told them what if they debit twice, they must sort the first issue first only to get a message few days after that they handed me to lawyers cause I'm not paying I was like wow... They really going to create a bad name for me for their mistake... I don't know what to do next