I kept getting to the end of the process, and it would not let me complete the transaction. The online price for her round-trip ticket from Tucson, Ariz., to Fayetteville, N.C., was $490.

I called Expedia's customer-support number. A representative tried to "help" me by charging $1,123 for the identical ticket. I asked why there was such a huge price difference and was told that I must have been looking at the one-way fare. I reluctantly accepted this answer.

The next day, I went back online to check prices, since my wife would also need to fly to North Carolina. Now the round-trip fare was $415 on Expedia - a $708 price difference. I called Expedia, and the representative told me I should contact the airline. I e-mailed the company, which responded with a ridiculous form letter about how to save on airfares in the future. Can you help us get our money back?

- J.D., Tucson, Ariz.

Answer: Ticket prices can fluctuate - and yes, they might vary between online and offline - but I've never heard of a fare doubling in a matter of minutes in the way you describe. I think someone, somewhere, hit the wrong button.

Was it Expedia? Maybe. When your online reservation didn't go through, you basically had to start from scratch, and it's possible that the agent didn't look very hard for a low fare. The fact that you were able to return to Expedia the next day and find an even cheaper fare suggests that something went wrong when you worked with Expedia's representative.

Then again, it could have been you. You mentioned that you kept getting to the end of the process and then having the site stall. That normally happens when you input the wrong credit card information, such as a wrong account number or expiration date.

Calling Expedia was a good idea. First, you want to make sure that the online agency didn't process your transaction without telling you. Otherwise, you would have made a multiple booking, and there's no easy way out of it. And second, you want to see whether Expedia can honor the fare it quoted you online.

Reluctantly accepting that story about the one-way fare? Bad idea.

You had to have known that you were looking at round-trip fares. In a situation like this, you could have hung up the phone, restarted your computer and rebooked your tickets through another online agency.

If I didn't know better, I would believe you were uncomfortable with using the Internet to buy travel. Which is completely fine. The next time you buy airline tickets, I would recommend using a human travel agent, to avoid misunderstandings.

The form letter Expedia sent to you was unacceptable. I would have appealed this to a higher authority. There are a few helpful contacts on my Web site (www.elliott.org/help/expedia).

I contacted Expedia on your behalf, and it apologized for your experience and refunded $300 to your credit card.