Poor service

I have a contract with neststart. I took a package that costs R200 per month, it comes with an App. My problem is that the App is shows incorrect location of the car. I have contacted Nestar several times with regards to this issue but I dont get assistance. If I request for cancellation of my contract they deny me and promise to resolve the isssue. They havecre-instalked the tracking device twice in my car but still I am experiencing the same problem. This has been going on for days. I wish I had chosen another service provider for my car tracker.