Question: I could sure use your help. I recently bought airline tickets to Europe on Expedia. The first leg of my flight was on US Airways, and the second leg was on Iberia.

I ran into a big problem on my return flight from Rome to Washington. I discovered that my paper tickets were not valid because they were originally issued on another airline. Expedia had made a schedule change.

Expedia claims it notified me that I needed to go to the Iberia ticket counter in San Juan to get my tickets exchanged. But I never received the message. I even called the company a week before I left to confirm my flights, but no one said anything about new tickets. When I checked in with Iberia for my outbound flight, we were given boarding passes and sent on our way.

Neither US Airways nor Iberia would issue the correct ticket. I had to pay about $5,800 for a seat on the return flight — more than the cost of the entire round-trip flight. I contacted Expedia after my return, but after more than an hour on the phone with a representative, I was told this was Iberia’s problem. What should I do? — Jose Morales, San Juan

Answer: Expedia should have told you about your schedule change and made sure you had the right ticket. Failing that, it should have pushed Iberia for a quick refund of the replacement ticket you had to buy.

And you? Well, one of the first things I recommend when working with an online agency is “white-listing” its e-mails. If Expedia tried to contact you, its e-mail may have been mislabeled as spam and trashed. You’d be surprised how often that happens.

Instead of calling to confirm your flights, I might have checked online. It’s possible that your reservation would have mentioned the ticket exchange. This in no way absolves your agent from failing to tell you about the change.

If Expedia altered your schedule, it should have done everything in its power to make the re-ticketing as seamless as possible. Paper tickets, which are technically obsolete, are neither convenient nor customer-friendly. To put it bluntly, you should have been issued an electronic ticket.

But let’s rewind to the moment you were stuck at the Iberia ticket counter and were being asked for $5,800. Your first instinct is to panic. That’s perfectly normal. But your second instinct shouldn’t be to reach for your wallet and pay whatever the ticket agent asks. Instead, phone Expedia’s customer support. The number to call when you’re overseas is 404-728-8787.

Expedia’s highly publicized “promise” guarantees it will take care of you in a situation like yours. “You can count on us to provide support throughout your trip,” it says. “Whether you have questions about your itinerary, have a change in travel plans, or need help resolving a problem with the trip you booked, we’re here to help 24 hours a day, seven days a week. Our job is to satisfy you!”

Had you contacted Expedia while the Iberia agent stood at the counter with an outstretched hand, waiting for your credit card, you might have saved a few thousand dollars and the hassle of several frustrating phone calls.

My point is, don’t wait until you’re home to resolve a complaint. There’s no time like the present.

Once you were back in the States, I think you might have made this easier by staying off the phone and sending a brief, polite e-mail to Expedia. Start at the front door by using the online form from Expedia’s site. If that doesn’t work, here are a few managers who you could write to: http://www.elliott.org/help/expedia/.

I contacted Expedia on your behalf. It promptly refunded your $5,800.