Paying for Non Existing Tracker

Ive been paying for tracker since April 2017 however my tracker is nolonger responding. I contacted the headoffice, they sent Ephraim (Technician) from the head office to come and fix my tracker on the 08 December 2017 however it was unsuccessful. He then called my wife advised her to bring the car on the 18th December 2018 to Tracker in Midrand as he is still struggling to fix the car. However it was still unsuccessful. He told us he will give us a call back book for our car so it can be properly fixed however he hasn't done that. We pay for tracker every single month however its been over 3months having a tracker thats not even working. What will happen if our car get ******? The service we got from Ephraim is soo poor and he doesnt care about customers. Ive called him several times he seems not interested in fixing our tracker.