Poor service

I had a tracker installed by Cartrack my tracking device has not been working for a few months and they been deducting monthly payments I then inform them of the device that’s not working and ask if they(Cartrack) can track my vehicle and find out where it standing a lady from customer care says she can’t cause my unit has a problem and that Cartrack will send a technician out to fix the problem a date is set and the technician doesn’t pitch up and I’m still sitting with the problem