Dishonest Southgate wheels

We purchased a Mercedes Benz at Southgate wheels in January, cash. On our way home driving the vehicle, we then realised that the car had lots of issues that were not disclosed by the dealership. Since it was already in the afternoon, we called them the following day that the car central locking system was not working, the car have to be locked manually, Secondly, the car Radio is only on for less than 2 minutes then it switches off. Which is safety hazard as the screen would switch off while you reversing, Thirdly the car reverse sensor were also not working, And the engine light is forever on. We have called almost every day since we bought the car, being tossed around from one person to the next, being ignored and endless promises on their side that never materialised. We have travelled to their offices on our own expenses and returned without getting any help. The car also had problem with the auxi****y battery and that’s the only thing they replace after 5 months and told us they would call us the following week with the date to book in the car for the other issues but we have been waiting and calling. The level of unprofessionalism and dishonesty seems to be the only thing they are consistent with!