Malfunctioning Inverter

I bought an inverter kit some two weeks ago and put it to work immediately after charging the battery. However, after one and a half hours of operation it suddenly stopped working. At that stage I had only a flat screen TV (70watt) and a DStv decoder in operation, therefore not overloading the system. All efforts to resolve the issue were referred to their technician, Muhammed, who asked for all the relevant info and a video. Since then, the problem was escalated to "Admin" and no further reaction received, despite several whatsapp reminders from my side.