Solar installation

Installation was done and CoC was not given as quoted. The inverter was faulty from day 1 and took me 8 weeks to prove to Gert the owner that it was in fact faulty. It was then promised in November 2022 to replace the the inverter. It is till today 22 June 2023) not done. The installed capacity is 4 kw for the solar and I only get 1.2 kw . I even went to the ombudsman and they sent Gert a letter I then received a message with promises and six months later the inverter still have not been rectified or repaired. The wiring used to the panels are not correct wires and after some the came back to relocate panels after initial installation wires were joined. Probably why CoC was never given. Please avoid as there is zero after sales service