Jeep Cherokee 2015 model

On the 26th of a March I have received a brand new Jeep Cherokee vehicle, I drove it for 13 days on the 14th day it gave me sign that says Service Transmission then took back the car to the dealer to check what's wrong with car it took them 13 days to find out what's wrong with the car and they are not sure if what they are saying its the truth coz really they are testing a new gear box installed in the car to check if the car is going to give same problem. They don't know what damage the gear box, I told the dealer that I don't want the car I want a brand new car as according to my safety the car came faulty from the manufacturer. They are telling me that i will get a new car when and if the car does not get fixed after they install the new gear box and that was instructions they got from Jeep South Africa.Now I'm waiting driving their Courtesy car for about full two weeks tomorrow is going to be the 3rd week. All I want it's a new car or to cancel the deal Because After I Drove 2000km,The Same problem May Happen Again And This Its A Very Expensive Car.The dealer communicate when and if I phone to check as what's wrong.