Horrible service from the dealership

They sold me demo model and the car started giving me problems with 4 to 5 months of driving the vehicle. I took the vehicle back and they could not fix the car because there was not a part for the 2021 model vehicle. I ended up driving loan cars that i could not even drive and manager was aware of it. I asked them to take car back and the manager promised to help me to get a new car . I used the loan cars for 2 months + and they said they will fixed my car, after I told them I do not want this car. the same car had minor faults when I took delivery. but they tried to sort the chips out on the car and the Salesman promised me there will be problems with the car. all i want is my deposit back, Now they want they loan back and want to give back the same car that was standing at the dealership for more that 2 months and what demo vehicle give problems and they expect me the drive it. Cleary they don't care about us but the sales they make .