Poor Client Service...Disappointed

Purchased a brand new quashqai in March 2018, car giving system fault. Taken it in over 12 times to garage. Nissan Sa say they cant help us futher. we want to trade in the car and they said the car is still to new it doesnt have trade in value. Very disappointed and frustrated with Nissan SA client service. My car sitting at the dealership and i still have to pay for something I not using....Please Help!!!!!