Poor service from cartrack

I have been with cartrack with the last couple of years. Lately their customer service has been nothing but absolutely pathetic It seems the consultants don't talk to each other and that their systems are not updated. I was recently retrenched and my account went into arrears.. I received a 45% discount on my arrears amount which I immediately paid. I also forwarded them proof of the payment. This is however where my problems started. They would phone me a minimum of at least 3 times a day, Monday to Sunday, enquiring about the outstanding amount that was paid.. Daily whatsups reminding my about the outstanding amount was also part of terrorizing me. Proof of this payment was sent to them on several occasions. They would phone me from the cartrack call centre, accounts department and even their attorneys. Trying to explain that I have paid doesn't help. Trying to talk nice to them doesn't help. Lately I have been extremely rude to them on the phone but not even that helps. The phone calls and whatsup messages on my supposed arrears keeps coming. I would never ever recommend anyone to make use of their services. I am already lying awake waiting for their first call reminding me that I owe them money. Phonetic bunch of people.