Worst experience

I asked for downgrade for one of my vehicle they installed faulty tracking unit for more than a year they never resolved that until their warranty was finished and they said I must pay them. When I told them I will no longer pay them they must cancel contract they said they will call back that was in April till to date they have not. 2nd vehicle I have month to month contract I called them for a downgrade and they were charging too much same story they said they will call me back that was also in April they just want me to pay them regardless of endless efforts sending them emails and calling them they refuse to help and always tell me their managers will call me back which it never happens.