Mix telematics breaks their promise

Good day. Early 2021 I was contacted by Mix telematics regarding my tracker device. I've been paying them R59 a month for three years then. The contract was also for three years. The lady on the line then told me that my tracker were no longer working and that that was for a few months already. They offered to put in a new tracker for an extra R100 a month. I immediately got upset because they knew that my tracker wasn't working but they let me pay them, even though if my vehicle would've been ****** in that time they wouldn't have been able to track the vehicle and I would have possibly been in breach of my contract with my insurance company. They only contacted me then because they wanted to renew the contract. I then decided to reverse the installments of the months that the tracker did not work because mix telematics didn't render me a service during that time. Now they telling me:Urgent; you are now more than 30days in Arrears on your Mix telematics account; Refno: You will be reported to a Credit Bureau 20days from this SMS; if no payment is received. Pay R 269.42 at FNB; This is wrong because they broke there contract with me first.