Faulty device.

I received a message from Cartrack that the unit is faulty. It was installed in October 2018. I was informed that the unit has a 1 year warranty and that I must pay a call out fee of R600 for the Technician to come out. I was also told that I have to pay a cancelation fee of R1700. My question is: Why must I pay to repair their product when I am still paying a 3 year contract? Looking at other reviews their units don't last beyond a year. I am not willing to continue paying for a service that I'm not receiving because of their poor product. Please help.