I wondered if the FT community has scared off the OP. Hopefully not, but at least she knows we speak our minds.

A couple of things -

1) As someone said, the daughter could be an inexperienced traveler. I'll give her the benefit of the doubt. My family didn't get to travel much when I was growing up, and I didn't go on my first "real" international trip (domestic were all road trips) until I was close to 20. I'd probably be a little freaked out about what to do if I miss or misconnect my flight. Not to the point where I would be sobbing, but maybe just a mild panic about what I should do next.

2) If she booked a flight with illegal connection (too short), part of the blame should be put on the agents for actually booking that flight. Part of it goes to the booking party for not checking the flight times for "reasonable-ness" (for most domestic, I believe the min connection time is 45 min).

3) I think we've established that 23 years old is not a "little girl". Sure, I have no doubt that the daughter had a really bad day, being bounced around like that by airlines and not being helped by seemingly anyone helpful. But these things happen. (Sometimes even the best planned vacation goes awry, let alone just a little delay). By 23, she should have been able to collect herself and calmly handle things by figuring out what to do next.

4) I'm sure the UA staff didn't appreciate being yelled at either, given that the issue happened through no fault of their own. Even if the OP didn't yell, I'm sure her frustration must have came through. Having said that, I'm not a huge fan of UA customer service either.

A side rant on UA's customer service:

UA's customer emails emails are backlogged (can take weeks to respond), and their system is outdated (which caused the reps to be unhelpful at times). Sometimes you get a good rep, sometimes not. I got a really bad rep once who really annoyed me. She put me on hold abruptly. I'd ask a question, and the next thing I hear is a "click...followed by like 7-10 minutes of hold music". She did this multiple times.

I am generally a very patient person, and I'm probably more forgiving that most since I worked in the client side before. Except she put me on hold at least 5 times, and she didn't seem to grasp the issue (what is she researching when she puts me on hold?) Finally, after more than close to 40 minutes of wasted time (of mostly listening to hold music), I finally snapped a little bit after getting increasingly annoyed of her putting me on hold (more so for her abrupt and unprofessional way of putting me on hold, rather than being on hold).

It was not my proudest moment. I wasn't yelling at her, but I raised my voice a notch and said sternly something like, "Look, you put me on hold xyz times already, but I don't think you got the issue. Let me restate what the issue is so you know what I'm looking to fix. The problem is that xyz...."

Once I am done (ha, I was even a little happy that I explained it well), I waited for her to respond or to acknowledge that she understands the issue. I waited, and then heard a click, followed by hold music again. I hate to do it, but I hung up on her. I got a far more competent and compassionate employee on the phone when I call back, who seems to "get" it.

If OP was venting about the CS experience, I get that. In the context of her daughter's experience, it's probably overblown.

Sorry, this post ended up longer than I planned. I guess you can write novels out of frustrated UA experiences!