Worst Service Ever - ZERO rating

Decided to put tracking devices for two of my vehicles however only one unit was installed. The other unit meant for my vehicle was installed in another persons vehicle. When queried about it they were adamant that the unit was in my vehicle. They sent a technician whom confirmed no tracking unit is installed. Two years later and I am still paying for the unit which was not installed. Every time I call I get no response and told that they are still investigating. Their service is PATHETIC!!!