You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you  for the day?

USER: I am Matthew Parker. Owing to an emergency, I want to change an existing reservation. So please help me in changing the reservation.

ASSISTANT: Sure, we are here to help you. Can you please wait for a while.

USER: Sure.

ASSISTANT: We  found a reservation, please forward your new reservation details.

USER: My source is Philadelphia, PA - PHL and destination code is IL - ORD. I want to fly on 02/28 and return on 03/01.

ASSISTANT: Thanks for sharing your details, please hold on for a moment.

USER: Sure.

ASSISTANT: Sorry we did not find any flights matching your new reservation details.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us. Have a good day.