You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what help can I do for you?

USER: I want to change my existing reservation, because of postpone of my examination, can you please help me in this?

ASSISTANT: Sure, may I know your good name please?

USER: Myself Ryan Roberts here.

ASSISTANT: Sorry, there is no ticket booked on your name to change the reservation.

USER: No problem.

ASSISTANT: Thank you for contacting us.

USER: You are welcome.

ASSISTANT: Have a great day.