Q: I booked a flight from Lisbon to Cleveland on American Airlines that was supposed to get in around 5 p.m. The airline first changed the arrival time to 5:20 p.m., which I was fine with. But then they changed it again to 9:22 p.m. My husband only discovered this a week before my trip. I never got an email notifying me.

This late arrival time threw off my plans, so I had to book a new flight on United Airlines that cost me an extra $900. When I called American, an agent made it seem like getting a refund would be no problem, so I submitted a request through their online form. To my dismay, American rejected my refund request and only offered me a flight credit that expires in a year.

Given that I had to buy a whole new ticket because of their unannounced change, is there any way I can get a full refund?

A: You should have received a clear and timely notification about your flight change. According to American's conditions of carriage, the legal agreement between you and the airline, you're entitled to a full refund if the carrier reschedules your flight by more than four hours.

The airline should have notified you of the schedule change well in advance. While they notified you of the first, minor change, the lack of communication about the second, more drastic change is unacceptable.

When you contacted American, the agent should have sent you a written confirmation of your refund eligibility. Instead, you received a verbal assurance, followed by a written denial.

While nonrefundable airline tickets generally don't qualify for cash refunds, significant schedule changes often warrant exceptions. The Department of Transportation mandates airlines to issue refunds for "significant" delays. Under its new consumer protections adopted last year, this is defined as any change exceeding six hours from the original departure or arrival times.

But this doesn't apply to canceled flights, and a look at your itinerary suggests that American canceled your flight and rebooked you on a different one. For a canceled flight, you always have the option of a full refund.

Bottom line: American can't keep your money and offer you an expiring flight credit. As I review your correspondence, it looks like you were stuck talking to an AI bot.

I contacted American. The airline reviewed your case and issued a full refund of your original flight to your credit card. Too bad it took my team's intervention to achieve this outcome. If you're ever in this situation again, remember to cite the contract of carriage and DOT rules to get what you deserve.

Christopher Elliott is the founder of Elliott Advocacy, a nonprofit organization that helps consumers. Contact him at chris@elliott.org or elliottadvocacy.org/help.