Car track unit stops working and you won't know until it's too late

My tracker isn't updating for the past 10 days, today is the 16th my last call to them was on the 12th they said they would find the location of my vehicle and call me back, 4 days later still no reply when I called the emergency number to locate my vehicle the lady tells me sorry my unit is faulty they can't locate it, it's stuck at the same location for days or weeks, pathetic service, there should of been ways in place to detect faulty units in yourls side or get alerted if a vehicle doesn't move for a few days, in the event my vehicle is ****** your call Centre will just tell me sorry the unit is faulty like they did today, I want to cancel my tracking unit it's unreliable paying R150 a month for a device that doesn't work