You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: Please help me to change an existing reservation as my plan to meet my grand parents got postpone due to bad weather conditions.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know on whose name the ticket has been reserved formerly?

USER: I am Timothy Allen.

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

USER: My boarding and landing airport codes are ORD and BOS.

ASSISTANT: Ok, can you please provide your dates of journey?

USER: I need to depart on Jan 5th and my return date will be on Jan 7th.

ASSISTANT: Ok, do you have any specifications?

USER: I need a direct flight.

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

USER: Sure.

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

USER: That's fine, you can book the ticket.

ASSISTANT: Your ticket has been booked with 1021 flight number.

USER: Thank you for your assistance in booking.

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