You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Jack Hall. I had planned to go on a trip, but it was postponed due to some reasons. Can you change my recent reservation?

ASSISTANT: Sure, please wait for a moment to check your details.

USER: Ok.

ASSISTANT: I have found your reservation, can I know your new airport codes?

USER: I want to travel from JFK to PHL.

ASSISTANT: May I know your travelling dates?

USER: I want to fly in the flight on 11/20 and 11/22.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: There is a Flight 1021 of UA airlines, shall I proceed?

USER: Proceed to booking.

ASSISTANT: Your ticket has been booked, have a nice journey.

USER: Thank you for your help.

ASSISTANT: Welcome.