Is there something i can do

I bought a car from carmax in greenville sc. I am paying 18,000 dollsrs for the car, and have had an average of a 1.5 problems each of the past eleven months i have had the car. The car will not crank or even turn over and the security light comes on. they have "fixed" the problem but it keeps reoccuring. this is the fourth time they need to fix it, but it goes deeper now. My wife has found herself waiting in freezing temperatures twice. she is 13 weeks pregnant and has come down with the flu. We are worried about the safety of our child. is there something that can be done for the trouble they have caused us.