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https://community.expensify.com/discussion/16402/can-any-economy-1-800-205-9716-fare-be-upgraded-with-expedia-flight/p1?new=1

Expedia will work with the Airline to find you a similar Flight, then
notify you through its app, by email, or by text. For urgent (for
example, same-day) changes, they may also call you. You can contact
Expedia customer service with questions if you don’t hear from them in a
timely manner after being notified of the cancellation.
Fees Expedia doesn’t charge a Flight cancellation fee. However, the
Airline might charge a fee to cancel, depending on the fare type
purchased. If this is the case, Expedia will pass this cost on to you.
You can see the Airline's fees, rules, and restrictions for your Flights
in your Expedia itinerary.