Quick to take your money and no support

I bought three Mecer inverters at R20 000 each, I need some firmware updates for them I spoke to the supplier MHN and to Mustek the importer, and get no response. I even e-mailed the Mustek Customer Relations Officer to no avail. When I bought one inverter and then two more, response was within minutes, but once they have your money? No response at all.