Acdc 5kVA hybrid inverter

I bought an hybrid inverter from acdc. It failed within the 1st year while under warranty. It was installed and worked fine for a week when it failed again. It took 2 months to get it "repaired" and R2000. On return I was told they had checked it and it was fine. When reinstalled it did not power up. They are now claiming it was a faulty installation. They want a further R2100 for repair. I bought the unit for R1000. I can buy an equivalent unit from Mecer for R8000.