Never to take responsibility

Bought a used and refurbished inverter from them that blew up soon after installation. They charged me to repair it saying it was my fault. Got it back but was still not functioning correctly and they refused to repair it for no cost. I took it to another repairer in Waverley Pretoria that repaired it in 1 day. Now works 100%. I showed the seller photos of what the board looked like after Inverters 4 All repairs. Gavin promptly accused the other repaired of being dishonest and misleading me when stating that some components were incorrect and some not even installed. He refused to reimburse the repair bill. I ASKED GAVIN FOR HIS TECHNICIANS CREDENTIALS, HE REFUSED. He also stated "I look forward to it" when I stated that I would look into taking legal action.