You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Can I know your name?

USER: Myself James Parker.

ASSISTANT: There is a reservation on your name. Let me know your travelling dates.

USER: I want to fly on June 16 and return on June 18.

ASSISTANT: Do you have any preference?

USER: I need a single connection.

ASSISTANT: Can I know your airport codes?

USER: My airport codes are JFK, DEN.

ASSISTANT: Found ticket with United airlines for price 100 having flight number 1011.

USER: You can proceed to booking.

ASSISTANT: Ticket is booked.

USER: Thank you.

ASSISTANT: Thank you.