Selling of malfunctional devices

Tracker installed malfunctional unit in my car that doesn't track movement of my vehicle. When I called them to report, I was informed that the unit is still under warrantee and they will replace it for free. Now they installed it and debited my account for the installation of the new device. this is so disrespectful of us as consumers and have no mercy to protect reputation of their own company. I want my money back