I'll give an example. I was caught by yet another example of a flight change that hadn't been reticketed. I called from the airport and to my surprise actually got through to an agent in "only" 15 minutes. The agent looked at my reservation and said because there had been a UuA on the return segment two weeks later there was nothing he could do to the ticket.

I informed the agent that I was at the check in desk, the flight was leaving in minutes, and if he put me on hold I would miss the flight.

He put me on hold, I waited thirty minutes with no answer. I bought a new ticket (which he could have issued of course) and nearly missed the flight anyways.

I've had exactly the same problem with AC with less time available and it was stressful but they called their internal help desk and got the ticket fixed.