Really bad service and then more!!!

I was moving to another country, selling my car, and emailed cartrack to ask what would be required to move the tracker to father-in-law's bakkie. They did not respond. I sold the car to We Buy Cars literally at the airport on my way out,still no response from Cartrack. I disabled the payments on my bank account and then suddenly they wanted to talk... It was too late, they had cost me the device as the vehicle with the device in had been sold. I paid the cancellation fee they demanded, R2600, under the impression they would refund me or at least refund part of it after investigating why their support team failed to respond to me in time, even though I got an automated message saying I would get a response in 24 hours. When I paid I asked to have a response from management telling me why they failed to respond in time.. I never heard from them and wrote it off as experience, I will never use them again. Now, I get an email from them telling me I still owe them R200!!!! The correct thing to do when you ***** over a customer is apologize , not keep *****ing!!! I asked for their management to be involved so they could figure out how they *****ed up and try fix it, or at the very least prevent it from happening to other customers, but I heard nothing back from management, which means either they don't care or it never got to them. ***