Tracker is still debiting me to date for a car I sold in 2018

Tracker is still debiting me to date for a car I sold in 2018. I tried calling them, Iwould be assured that it wont happen again and yet it happened. I was then told after i called them again that to close the account i was liable for about R900 ,don't remember the exact amount. I paid it and the still was debited. Now they have gone from debiting R300 to R500. Is tracker a **** or something I called and got a letter to say that my contract with them has been terminated and yet I am still being debited. I blocked them from debiting and the by-passed the block. What on earth does tracker want me to do to get them off my back. I regret ever signing a contract with them, 2 years after selling a car I'm still being debited, come on tracker this is ridiculous stop ******** me I work hard for my money. Even when I try to things right I end up loosing come on. THE CANCELATION LETTER READS THAT THE CANCELLATION HAD BEEEN REQUESTED FROM 31/12/2019. I WANT MY MONEY!