A: American Airlines should have transferred your luggage to Finnair. But you're correct; Finnair was responsible for delivering your luggage to you in Paris, and it didn't — not until the next day.

Compensating passengers for incidentals while they wait for their luggage is something of a gray area. I've seen airline agents hand passengers like you cash to buy new clothes and toiletries. And I've seen them deny any responsibility.

The page dedicated to lost luggage on Finnair's site (www.finnair.com/ca/gb/information-services/baggage/lost-delayed-damaged-baggage) doesn't mention anything about compensation for incidentals, nor does it state that there's a required 21-day window for applications. Rather, it asks you to fill out a baggage tracing form within 72 hours, which you did, and suggests you wait patiently.

I like the way you took the initiative on this one. You started contacting people until you got answers and results. (I list the names and numbers of both the Finnair and American customer service managers on my consumer advocacy website. Here are the Finnair contacts: elliott.org/company-contacts/finnair/. And here are the American contacts: elliott.org/company-contacts/american-airlines/).

From my experience, the best time to negotiate reimbursement for incidentals is at the time your luggage is lost. Agents are often authorized to offer vouchers or allowances for clothes and toiletries while you wait for your belongings. If possible, make sure you have everything in writing.

Bottom line: Even though Finnair didn't drop the ball on your luggage, it is technically responsible as the last operating carrier. A 70 euro credit is a good start, but it doesn't cover the real expenses you had.

I contacted Finnair. As a “gesture of goodwill,” the airline agreed to cover $220 of your expenses, which you accepted.

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.