AUTOMARK PROMISE USELESS

I bought a secondhand Toyota Landcruiser pick up from Oranje Toyota Kroonstad. This vehicle was a Automark vehicle with a full service history. Before I bought the vehicle I asked the salesperson to ensure everything was working because I don't want to have expenses after the six months warranty expires. On the 17 July 2015 I took this vehicle for its 120000km service about 6000 km from where I bought the vehicle. The local dealer told me that the front lockers where pirates and not working properly. After a long struggle this was replaced. I tried to use the rear difflock for the first time on 22 September 2015 to get a stuck trailer out. It didn't engage. I took the vehicle to Toyota and they confirmed the actuator is not working. Oranje Toyota don't want to replace the part as they checked the vehicle before delivery. They didn't even pick up the faulty 4X4. Toyota SA doesn't want to sort out the problem either. My big problem is the fact that I drove 8000km with the vehicle. A vehicle that came out of warranty July 2014. Should one be spending this amount of money on a suppose to indestructable vehicle. With 121000 km on? I didn't check working parts as they should have.