Dissapoining service

I am highly disappointed with the service we have received from Altech Nestar. A unit was installed in my wifes vehicle on the the 4th of July 2018 at the dealership. We took possession of the vehicle on the 7th July and ever since the unit has not been working. The GPS position shows the vehicle is somewhere in the Atlantic ocean and the tags and panic are not linked to the vehicle. We have called Altech Nestar so many times regarding this issue I have lost count. They always promise to get back to us and nothing happens. A lady by the name of Zanele called and promised to back to us but nothing. They have admitted the unit is faulty and the need to replace it. Can Altec Nestar at the very least do the right thing and let us pay for a service that they supposed to be providing. Account number ********** 3.