Poor service and no response!

My cartrack stopped workin 2 years ago. I have been contacting them eversince. They said the unit needs to be replaced and I must pay R600 for it. I booked a replacement after several emails i finally got a respond. After booking the replacement I received a sms to say the problem was resolved ticked closed. They never came to replace it. I have been unable to get hold of them eversince. This is poor service and theft as they are still taking money from me every month but if my car gets ****** they will not be able to track it. Why am I paying for my car to be tracked but its not being tracked how can they take money for a service they are not even providing?