I had a schedule change a couple of weeks ago and UA charged me without notifying me. I found it on my credit card receipt. They said the taxes (though they could not tell me exactly which ones) had gone up since I had purchased the original ticket and I would have to cough up the extra amount or not fly and lose the value of my existing ticket. I guess they figure if they do enough schedule changes, they can charge the existing customers with nonrefundable tickets enough to get out of going through bankruptcy.