You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Gary Campbell.

ASSISTANT: How can I support you at this moment?

USER: I would like to change my existing reservation, due to postpone of my live concert which was going to be held at Washington.

ASSISTANT: Sure, I am here to help you.

USER: Can you please assist me in changing?

ASSISTANT: Sure, please wait for few minutes, let me check with your existing reservation status.

USER: Sure, I will be waiting.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: Ok, not a problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.