Car track is tipping us off

I have a tracker in my car which was installed by car track. It was replaced I every second month in 2017 in 2018 the unit stopped working it wasn't even 3months after the last unit was replaced I received a phone call from car track saying I need to replace my unit as it was not functional I agreed. A few minutes later I received a phone call that I am going to have to pay for the replacement as the unit is out warranty. I then asked the consultant why must I pay because the unit was not even fully operational for even 3months suddenly I must fix it? she said my contract stipulated that after a year I will pay for any faults to be repaired. I refused because I felt that the company knew that the units they are using are not reliable they need to be replaced every 2nd or 3rd month howmany 700 am I going to pay in a space of 3years?Car but they continue to use them any way. The unit has not been working since late 2018 and the debits are still running I asked for the unit to be removed, I was told I need d to pay R1800 for the contract to be terminated. I have been donating money and now I'm tired. Locations were never accurate on the app when you call the call Centre they say we will call you back so dissapointing.