Bought a new car

I bought a brand car on the 27th May on my arrival at my house I noticed that the handbrake and the car seat are not working. I phoned the sales man on the 28may as it was late to return it that same day . The only thing they could assist me with is to return the car for repairs. I told them that I do not want that car I want a new car I signed a contract for not the car that is still on repairs . The car is still with them trying to order parts . Fortunately I have returned their spare key. Kindly advise on the matte