Poor service

Since cartrack device installed in my car on August 2020, the device never worked and i reported the matter to cartrack since they promised to send technician to repair the faulty tracker device till to date. December 2020 I decided to stop making payments to cartrack because of their poor service. The cartrack keeps calling me demanding their monthly payments and I kept on complaining about the device that is not working and also to cancel the contract. All falls on deaf ears Currently I'm summoned to pay all premiums since October 2020 to date on something that is not working even though I sent several complaints to them without assistance.