Unhappy with Hyundai after sales service.

I purchased a new Hyundai Venue from Hyundai Sandton in September 2021. First complaint was how the additional charges were loaded 100% mark up from the installation teams. (Windscreen crystal treatment, Smash & Grab, and Netstar Liquid Capital Insurance) I was advised that I was given the full service package and for the next 3-5 years I would not have to worry about any additional costs. However besides the above not been true, I recently found out on my 45k service (standard advertised service agreement) that I have no additional service plans available. Liquid Capital has also expired after 2 years. From the start, even before the first 15k service I experienced a strange thing that when I put my car into reverse it engages everything to show it should reverse and does nothing. It does not move, the time it takes to engage reverse depends. there have been times I have to do this action 3 or 4 times, other times just once. It was reported to Sandton and a video sent to them on a few occassions. My vehicle was taken to them to check and each time i was advised they can find no issue. I then took my vehicle to Hyundai Strydom Park and I have sent the service manager about 5 videos of what happens to the car and he has had the car for a week. He has now advised that they find no fault with the car. He also advised that my car which is advertised as a very fuel efficient vehicle is running as it should. It is extremely heavy on fuel. I am not happy with a car with an intermittent fault. I can not trust my vehicle will not get worse and it seems Hyundai is just brushing this off as nothing.