Cartrack spamming me with marketing calls

Cartrack is constantly calling me on my mobile even thought I keep on asking them to remove me from their database and to NO LONGER CALL me. I have not received any emails with the option to OPT OUT as per the POPI act. How do we get rid of Cartrack marketing calls? I have never agreed to them using my mobile number for marketing purposes and asked many times to remove me from their list!