The absolute worst customer service!!

I sold my car in 2021 but didn’t immediately cancel my tracking device. Eight months later I realized that I’ve been paying for a car I no longer owned so I contacted Mix Telematics to cancel. I was told to send an email which I did and also received an automated acknowledgment email. The following month, same story I was debited, again I called and sent an email. Months later I receive an sms from lawyers that I’ve been handed over for R400 odd rands. I contacted the lawyers, they didn’t have my profile then I called Mix again, they confirmed that I do not owe them, in fact they owe me. This morning I received another sms from legal. I don’t know what else to do.