Disappointing Netstar

I purchased a new vehicle on 20/12/2025. The vehicle was 100%. Netstar installed a tracking device on 24/12/2025. Two days after, the vehicle would not start and the passenger airbag light comes on. Netstar came to my premises on 05/01/2026, to look if the device is not the problem. The technician called me, stating it is my battery that is the problem. 06/01/2026, the battery was sent to a battery centre, charged and tested perfect. I asked Netstar for a diagnosis certificate showing how they see the battery is the problem, I have not received this as yet. The only possibility is that the technicians are not properly trained to work on all vehicles and did this installation incorrectly. My vehicle is still not starting if left over night. I await resolution from Netstar.