Bad service on car deal, refusing to pay costs on damages car was sold with

Me and my son bought a BMW Coupe, 2011 model from Concept Auto, in Port Elizabeth, salesman, Fadiel on 10 June 2022. We had to pay R20,000.00 deposit. We are from Kathu, in the Northern Cape. They knew we were coming this distance with the Intercape.

After closing the deal, we immediately drove back, because we have a long road ahead of us. When we were +- 20 minutes out of PE, the red engine light came on on 120km/h. My son immediately phone the salesman, Fadiel and he told us that we must take the car for a diagnostic test to our nearest BMW dealer and that they, Concept Auto would pay for it. And if their is a problem that the AVS service plan that we took out would cover it. We had to drive a slow pace, because the engine light came on continuously.

Long story short, we got home and struggled for weeks to get to a BMW dealer, because we are 300km away to the nearest dealer and had work responsibilities first. We had to drive 3 times up and down on our own cost, accommodation on our own cost and they refuse to pay out the diagnostic test. The salesman told me on the phone in sarcastic tone, that he will not run away. The engine plan payed out for damages on the eccentric shaft and Concept Auto did pay the excess, but they still refuse to pay out our diagnostic and don't return our calls. They sold a car who was not worth the retail price. Banks whose accepted them for finance, must know this.