Forcing debits on my account

Good day, I am having a problem with CarTrack, I subscribed with them on a 3year contract I then sold my car before 3years, I called them and they told me to cancel or move it to the person who bought my car, which I do understand that is on my contract. So they gave me a choice to cancel for R1700 and I was left with something like 7months and I did not have cash on me, so I agreed to pay a monthly premium until the end of the contract which was last year June.

Okay, July they did not debit, at the end of August they started to debit my account again , when I called them they told me that I need to cancel for R900. I called my bank but my bank told me that even if they stop them from debiting if Tracker changes their REF it will still debit, so they advised me to talk to them.

Last month they called me and I told the lady who called me that please stop this debit order and told me that the reason for her call is that I owe them R950, areas. After they debited R100, R150, R317 I moved my money to another account and I got an SMS when they were debiting another R150

What makes me even more angry is the fact that

1. After 3years automatically my account goes to pay as you go, meaning If I don't pay, They don't cover me but they insist on harassing my account even though they know that I do not have the car anymore.

I will never ever recommend any one to join this ****, Now I am forced to close my account and move all my debit to the new account.