Drivers Select review: used car without spare key

I bought a Nissan sentra from driversselect last week and was given only one smart key. When i inquired driversselect, they said the 2nd key was not given when they acquire the car from previous owner, so they can give me only the one available key. Also, they say that they informed me about this, but they never did inform me previously. And if i still need the spare key, they ask me to pay for it. Howncan i handle this situation.