Poor Service / none working installation inverter

They installed my unit a week ago and the service is pathetic. They don’t answer their calls and WhatsApp everyday since installation. They don’t give you a tutorial on how the system works and how to connect the app. The installer couldn’t assist as he doesn’t know himself. The battery only charges 25% and inverter does not switch over during load shedding. Now I’ve paid for a system that does not work.