Faulty inverter

I recently bought a SPF 5000 ES Growatt inverter which after 3 months switched off and refused to switch back on, l tried contacting them telephonically but this proved fruitless because their lines were down, l eventually replaced the inverter and dropped off the faulty on for a refund, l was told by staff that they dont give refunds and they will have the inverter repaired, l insisted that l replaced the unit and requested a refund because of the current loadshedding.... its been 3weeks now and have been reffered to someone else...please help