My flight transferred to a train — my ticket didn’t

A: After a 40-hour delay, and assurances by United Airlines that you had a valid ticket from Frankfurt to Dusseldorf, the least your airline could have done was keep its promise to you. Instead, a United Airlines representative gave you a non-working confirmation number.

Let’s back this up a little bit. How did United Airlines get on the hook for train tickets on the German railway? Through the miracle of code-sharing, that’s how! Your travel agent can book a trip from San Francisco through Dusseldorf via Lufthansa with a connection to Frankfurt on Deutsche Bahn.

That’s convenient, but it also means Lufthansa is responsible for getting you from Frankfurt to Dusseldorf. It looks as if something got lost in translation between its code-share partner, United Airlines, and Deutsche Bahn. But if Lufthansa sold you the

We booked round-trip flights from Frankfurt to San Francisco through Lufthansa. The final leg of our trip, from Frankfurt to Dusseldorf, was on Deutsche Bahn, the German railway.

Our return flight from San Francisco to Germany was supposed to be a code-share on United Airlines. The airline canceled our return and we were rebooked on a flight that got us back to Frankfurt 40 hours later.

A United Airlines representative in San Francisco told us that she had reserved three seats on the train for the next day. However, there were no reservations, and the booking number given to us at the counter in San Francisco was unknown at the Frankfurt Airport.

We had to pay 509 euros for new tickets to our final destination, Dusseldorf. I have tried contacting United Airlines by various channels, including phone and email. They keep ignoring us. Can you help me? ticket, then Lufthansa is responsible. Full stop.

I list the names, numbers and email addresses of the United Airlines customer service managers on my nonprofit consumer advocacy site. I also have the Lufthansa executive contacts. A brief, polite email to one of them might have fixed this for you. But based on a review of your paper trail, it looks like you tried to contact a lot of people at United and Lufthansa, to no avail.

Forgive me for going off on a tangent, but this is not what regulators had in mind when they approved code-sharing arrangements for airlines such as Lufthansa and United. They meant that Lufthansa should take full responsibility for your trip from

San Francisco to Dusseldorf. And they definitely didn’t mean for you to be ignored when you tried to persuade the airlines to fulfill their obligation to you.

I think you might have underscored your complaint by copying the U.S. Department of Transportation or the German Luftfahrt-Bundesamt, which regulates airlines domestically. I think a brief, polite grievance by email to the airline authorities might have sent a clear message: If you sell a ticket on the train as a flight, then the airlines should ensure their codeshare partners can accommodate passengers in cases of flight delays or cancellations.

You contacted Lufthansa and it agreed to reimburse you for the tickets and pay you additional compensation of 140 euros.

Christopher Elliott is the ombudsman for National Geographic Traveler magazine and the author of “How to Be the World’s Smartest Traveler.” You can read more travel tips on his blog, elliott.org, or email him at chris@elliott.org.