If you need to change a flight after you've already booked it with Expedia, you'll have to call their customer support team at $????-????????????-????????????-????????????????$. (inside the U.S.) or $????-????????????-????????????-????????????????$. (international). Absolutely, Expedia provides a 24-hour Seat Selection. If you need to cancel your flight, you can do so without a fee within 24 hours after your booking. For your convenience, cancellations can be made either online or by contacting their support at $????-????????????-????????????-????????????????$.