Q: I had to repurchase tickets at the last minute after our international travel had already begun. United Airlines canceled part of our itinerary without notice or remedy.

My wife and I had booked tickets through United.com from Albuquerque, N.M., to Reykjavik, with stops in Houston and Frankfurt, Germany. When we checked in at Albuquerque, a United representative told us that we couldn't check in for our flight from Frankfurt to Reykjavik because Icelandair was not a United codeshare partner. They assured us that we would only need to pick up our luggage in Frankfurt and take it to the Icelandair ticket counter.

We flew to Houston, and tried to check on the status of our Icelandair reservation. But Icelandair's website and mobile app could not find it. Icelandair's customer service line told us that the reservation had been canceled by the issuing travel agency the previous day. I presume that United itself was the agency. The United gate agent in Houston could not help.

We had to repurchase the seats for $1,959. It would be appropriate for United to refund that cost.

A: What a nightmare! You booked your tickets through United.com, so it's responsible for getting you to your destination. It doesn't matter if United has a relationship with Icelandair or not. The buck stops with United.

Normally, you would find out about a problem well in advance of your flight. A last-minute call to Icelandair might have revealed the problem. But if you buy a ticket on United.com, and it sends you a confirmation number, you should be confident that you actually have a reservation for all the travel segments.

I don't think you had much of a choice about buying a new ticket. If you had missed your flight in Frankfurt, it would have screwed up your entire vacation — car rental, hotel stay, tours, etc. You were cornered and had to purchase a more expensive, last-minute ticket. This was something United should pay for.

You contacted United in writing and did an excellent job of keeping a paper trail. In response, the airline offered to refund the unused leg but nothing more, claiming a "desynchronization of your ticket" caused the problem.

"Due to operational changes, we're unable to guarantee flight times or aircraft types, especially when the flight is operated by another airline," the representative said. United apologized and deposited 5,000 "goodwill" miles into your account and refunded the canceled leg.

That's a good start, but United needed to step up and cover the cost of your new flight. I contacted the airline on your behalf, and it issued a full refund.

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