Slimline model disappointment

I bough a Defy Slimline plate and oven set 16-12-2022 from GAME stores, it was on special. Installed it & 7-8 months later the set started to give issues, tripping the main switch & showing flames between plates & oven. Logged a call with the Customer center they sent a technician, thanks.1st report 23-08-2022: something burnt due to load shedding power surge & advised that part will be replaced. 2nd report new technician 24-08-2022: Replaced the part & advised that if oven is on they then only 2 out of 4 plates should be switched on otherwise the part will burn again!!! & not switch to the highest level if the oven is on!!! If I knew that I bought a set that operates like this, I should have went to a second hand shop and bought a 2nd had/used set and another brand if possible. Little did I know that a new oven and plates would have to settle malfunction. To add on to that the technician left my oven un*****ed/not assembled properly. *****s are in the oven and job card is closed!