Mustek - Poor service

Three months ago we bought a Mecer solar inverter and last week the inverter was damaged during a thunderstorm by lightning. We took it back to Mecer since it is still under guarantee, but was told that surge damage was not covered and the repair costs would be R7000. There was a surge protector installeThe inverter cost R11000, so now we have to pay an extra R7000 for something that was out of our control? And the Mustek employee that helped us was extremely rude as well.