Very very bad customer service (useless company)

My Cartrack’s account was handed over I paid off the account when I called to find out what is the way forward they told me I need to pay another R1800 which I don’t understand what is it for because I paid of my debt with them I really wanted to continue with it but I’m done with it’s bad treatment of clients. I sent emails of paid up letters but they haven’t contacted me back but they used to contact me every hour when I was in arrears