Acdc hybrid inverter

20 months ago I bought a 5kw inverter from the Pinetown branch. The unit was installed in a remote location (mtentu river mouth on the wild coast) and was used periodically(maybe 1 week a month. The unit failed within the first year which they repaired under warranty. On reinstalling the unit it worked well fora week whereupon it failed again. It was sent in for repairs at beginning of December 2021 and, with a lot of nagging, was returned in the 1st half of February. I had been reassured it had been tested. On reinstallation it lasted 1 second and died. I returned it to them 2 weeks ago with insurance from them they would look at it urgently and get back to me about a solution. I have tried on various occasions to contact the person who said he would get back to me but my calls are not answered.