No after sale service.

I bought a Deye 5Kw inverter and a CFE-5100 battery from them as a system. After struggling some time with an error on the battery and a battery disconnect on the Deye I found out that these two units is not compatible and needs a firmware upgrade to be able to work together. After many e-mails, WhatsApp's, and phone calls (all unanswered) and a week later I got them to update the Firmware for the Deye. Now I am still waiting for them to upgrade the battery. In the meantime, the customer is out of his expensive system. What do you need to do to get after sale service from Setsolar Epping?