You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I  help you?

USER: I am Robert Baker. My scheduled examination dates has been postponed, could you please help me with changing my recent reservation?

ASSISTANT: Sure, just a moment please.

USER: Sure, take your time.

ASSISTANT: I found  your change reservation, help me in providing your changing details?

USER: My source airport code is DEN  and destination airport code is DCA.

ASSISTANT: May I know your travelling dates please?

USER: I would like to take off on 07/20 and return on 07/22.

ASSISTANT: There is a flight with a single connection, can I proceed for booking in 1006 flight?

USER: May I know the ticket fare?

ASSISTANT: It cost you 200 only.

USER: Please confirm the booking.

ASSISTANT: Your booking is done in UA airlines.

USER: I really appreciate your help, thank you for your service.

ASSISTANT: Thank you for choosing us.