BAD CUSTOMER SERVICE FROM U.S. Airways

I made a reservation for my nephew (14 yrs old) and my son (8 yrs old)to come home after the thanksgiving vacation with my son's father, came to find out at the time of check in that not only they couldn't fly that day but I also had to pay extra. My frustration comes when you search for the cheapest flight but yeah they don't disclose all the fees. I disclosed their ages before I paid and don't understand why they let me procede with the reservation and even that why they did not tried to get a hold of me even a few days before they flight also, if i cancel the flight my money was not going to be available until 7-10 days after. I seriouly think U.S. airways need to upgrade they system because not everybody has a money tree in their back yard.