What to do about drunk parents?

My stepfather and my mother are drunk at least 3-5 nights of the week. This really bothers me and I tried to tell them how it makes me feel. I go to sleep crying, and push them away. It just really makes me angry because they cant be responsible when me or my stepbrother are around. I am afraid that one night there will be an emergency and who will drive!? Both me and my stepbrother are too young and what am I gonna do? Call the ambulance? Then they'll see this mess. My parents aren't alcoholics, or at least I don't think they are. I just wish I could get through to them! How can I do this without causing a fight?