Can an airline change a reservation booked through Expedia?
If I book my flight through Expedia, can the airline make changes to that reservation (e.g. if I wanted to change my return date), or do I have to call Expedia directly?
just had an one-hour phone call with Expedia trying to change my flight, but still couldnt .. it is really annoying
Yes, the airline can make changes to a ticket issued by a 3rd party.
Whether they will make changes is a different matter.
In general, the ticket is deemed to be 'owned' by whoever booked it - generally either the airline itself, or a 3rd party travel agency. That party is the one that has been paid to issue the ticket, and is generally responsible for making any changes at least up until the start of the first flight.
So in general, any changes - at least before the start of travel - will need to be made by Expedia.
Some airlines do give you the option for them to "take over" the ticket so that they can make changes, however (at least in the US) they will generally charge you for doing this. eg, the United Airlines Contract of Carriage states :
UA will assess a 50.00 USD/50.00 CAD fee to assist with a voluntary change on tickets originally issued via any external ticketing source (travel agency, internet agency, other airline, etc.). The fee is non-refundable and applies in addition to all applicable charges.
American Airlines call it a "External Reservation Handling Charge", along with a US$25-35 fee.
This fee may be waived if you are a high-level frequent flyer, or potentially if you are on a high fare ticket - but often that's at the discretion of the phone agent.
You can always try calling the airline, especially as every airline has slightly different policies, but for something like a change of date of a flight I would not expect them to assist you without paying this fee. If your travel has already commenced then you might have more success.
I know that some airlines won't take over 3rd party tickets until 24 hours before the departure of the first flight, so timing can matter too
I get the idea that 3rd party services like Expedia "own" the ticket in the same way that if I buy a ticket for a friend, I own it and my friend can't cash it in a refund without coordinating with me. But why don't airlines allow 3rd party services like Expedia to transfer ownership of the ticket to the passenger? I've seen many airlines deal with frustrated passengers at the airport who can't understand the difficulties adjusting flights they "bought". Wouldn't everyone be happier if ownership transfered?