You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: Owing to an emergency, my live concert got postponed, so I want you to change my existing reservation.

ASSISTANT: Sure, I am happy to help you with that. Can I have your good name please to check your reservation status?

USER: Sure, Gary Williams here.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Gary Williams, no reservation  has found under your name to change.

USER: Ok, no issues. Thank you for your assistance.

ASSISTANT: Thank  you for choosing us, have a good day.