You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Charles Gonzalez.

ASSISTANT: Charles Gonzalez, how can I aid you today?

USER: Owing to an emergency, I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, I am here to help you. Hold on for a moment. Let me check.

USER: Ok.

ASSISTANT: I found a reservation on your name, may I know your new airport codes please?

USER: My airport codes are PHL, BOS.

ASSISTANT: Ok, can you please provide your travelling dates?

USER: I want to fly on Jan 31 and return on Feb 02.

ASSISTANT: Do you have any other requirements?

USER: I would like to depart in the afternoon time.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Ok.

ASSISTANT: I found a flight for you with Frontier Airlines and it costs you 100. Shall I proceed to reserve a seat in this single connecting flight?

USER: You can proceed to booking.

ASSISTANT: Your ticket has been booked with 1000 flight number.

USER: Thank you.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.