got sold a car with spare key not working

I bought a car at KIA motors and the sales person as good and friendly. He assisted me all the way. When i went to collect the car, the other key was not working and he told me that it will take a week to get a new battery. Its been almost three weeks and when i call him, he doesn't return my calls. I am under the impression that he sold me a spare key that does not work. Martin is good consultant and i gave him 5 star rating, but now i am disappointed.