Faulty product refusal to repair

We signed a contract for a Mercedes 180CDi 2005. Two days later we reported the gears scratch and requested it to be checked. After two weeks they eventually said we could take the vehicle to their workshop to be checked. It was reported to us that the gearbox links were faulty and they will not repair it. The sales manager agreed we can cancel the contract as we were not willing to purchase a faulty vehicle. This resulted in us having to pay R4990 to them for registration and delivery costs. We really advise any consumer to please have a vehicle checked by an external third party to avoid you occurring costs for a faulty product. We really did not expect a large institution being extremely poor in communication and assistance. We are located 360km from the dealer and had lost a lot of money driving up and down besides all the leave we had to take for the travelling.