All ( I mean ALL) airlines US airlines are pathetic. I had faced this issue two times in the past and all they do is just blame each other. They care about numbers and do not care about customer satisfaction unlike internal airlines.

If you are making travel arrangement for your parents then better you send them with someone or at least do not make any connecting flight within US or Canada. I learned it in a hard way. No matter what they say, never make any connecting flight within US or Canada.