Mid/rear Seats Assembly problems of the 2011 Toyota Prius

I am an excellent driver. I purchased this Prius in the summer of 2011. We (my wife and young daughter) were proceeding on juanita drive n. E. In kirkland, wa. My wife and I agree that our speed was approximately 30-33 mph and that there were approximately 3+ car lengths between us and the vehicle in front of us. The weather was dry and sunny. Suddenly, a vehicle three vehicles ahead of us stopped to make a left turn, and the two vehicles behind it were able to stop. I immediately applied my brakes to the floor as soon as I observed the stopped vehicle ahead. I felt no response - no gripping of the brakes or gripping of the wheels to the road, no squealing, no skidding, no sense of the brakes slowing the vehicle in the three seconds I applied them. Due to vehicles in the opposing lane, a narrow road and no shoulder (a ditch with telephone poles on the right), I was forced to design the least harmful impact - my front right corner to the rear left corner of the vehicle in front. The impact tore open the right front of the vehicle, shattering the windshield next to my wife and causing her legs to fly up and strike the dashboard, injuring her legs in several places. Her airbag did not deploy. My 7-year-old was in her car seat in the back seat. The larger split back was behind her. The back became unhinged at impact and flipped forward, forcing my daughter's upper body forward. She sustained minor facial injuries. While it is possible that the airbag non-deployment was appropriate (I am not certain of this), there is no question that the braking was soft, squishy, non-existent, and the back seat should not have become unhinged.