Tracker unit not even installed in correct vehicle

Just recently, I received a letter from Tracker, stating that the tracking unit in my vehicle was not performing correctly die to a power supply problem and that they would be replacing the unit free of charge. I subsequently came to know after calling them, that the tracking unit in mention was associated to a different model vehicle and registration number!!!<br> <br> Long story short... I have been paying a monthly subscription for a non-existing service for almost 20 months now.