False advertising. Sold features that don't work

We bought a brand new Clio 4 expression last year June from Renault Northcliff. The sales rep at the time was an intern and made empty promises with regards to delivery of the vehicle. After being filled with lies and all sort of stories we eventually fetched the car when it was ready. A few months thereafter we realised that the car is not metallic but they sold it with metallic (which is currently still in the installment). We went to the renault branch and spoke to the manager (Shaun), who promised to get the finance manager to rectify the situation with the bank and give us feedback, we're STILL WAITING. We are experiencing a lot of problems with the car, it rattles, the driver window makes noises, the boot makes noises (according to Shaun this is normal), the car makes weird sounds when you start it after driving for a while, the sound system switches to the radio by itself and MOST ANNOYINGLY the stop-start function has NEVER worked and the car is already over 15000 k's. The workshop manager (Alvin) could not believe that the stop-start hasn't worked by now. Him and Shaun gave us different stories and I am just Fed up by now! Don't want this car anymore! Contacting my lawyer.