Q: We made a reservation recently on Hotels.com for a hotel in Paris. When we arrived, the hotel informed us that it had canceled the reservation due to an issue with the credit-card transaction. Apparently, not all U.S. credit cards are accepted in Europe, which we also learned when we tried to buy train tickets from a machine with the same credit card.

Our hotel told us that it had notified Hotels.com of the credit-card issue and cancellation before our arrival. It even showed me a printout of the email. However, Hotels.com never notified us of the credit-card problem, nor the cancellation. The hotel had only one night available, so we had to find another hotel at the last minute for the three remaining nights.

We called the Hotels.com number in France, and the agent stated that they had the cancellation in their system. But after speaking with several representatives, Hotels.com refused to put us in another hotel at the same rate.

We were able to finally locate another similar hotel nearby, which we also booked through Hotels.com, but the rate difference was $360. I have contacted Hotels.com, asking it to reimburse me for the difference, but it refuses. Can you help me? — Judi McManigal, San Francisco

A: If the cancellation was in Hotels.com’s system, then one of two things might have happened. Either Hotels.com failed to notify you of the cancellation, or the email never made it to you because of your spam filter.

It’s difficult to know whose fault this was without some digital forensics. And in the end, it probably doesn’t matter. When Hotels.com learned that you were in Paris sans hotel, it should have tried to help you. Leaving you to fend for yourself isn’t my idea of good customer service.

You might have avoided this by calling Hotels.com or logging on to the site and verifying your reservation. If the reservation had been canceled, then it wouldn’t have shown up, and the situation could have been addressed before your flight. Also, consider ‘white-listing’ emails from Hotels.com, so they’ll always get through.

The thing is, when you’re stuck in the hotel lobby, all you can do is call your online travel agency.

I contacted Hotels.com on your behalf. It refunded the $360 difference.

Christopher Elliott is the author of “How to Be the World’s Smartest Traveler (and Save Time, Money and Hassle)” (National Geographic). He’s also the ombudsman for National Geographic Traveler magazine and the co-founder of the Consumer Travel Alliance, a nonprofit organization that advocates for travelers. Read more tips on his blog, elliott.org or e-mail him at chris@elliott.org