Faulty device and poor service

So I bought my car on the 15th of June and the tracking device was paid for 3yrs by the dealership. After several calls, Netstar finally came to fit after few days. Ever since the device was fitted, I have been receiving msg of battery being disconnected even if am driving. I contacted them and again after several days, they sent a technician to come fix the device. The technician spent the whole 2hrs only to tell me he can't locate the device ????????♀️. I had to call the person who fitted it and asked where he put the device, I mean really ????♂️?!!! Finally the technician was told where the device is. He spent another hr n then left. I have been receiving the same msgs ever since and I called their office again, using my airtime and after hrs of holding the line, the lady told me someone will call me to confirm when the technician will come and do the "fixing". I told her they should rather install the new one cos it's clear whatever they fitted there is faulty. Till this moment no one has contacted me nor came to install the device. Now, nobody is picking up the calls. I have tried to call but????♀️