You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to postpone of my event.

ASSISTANT: Sure, I am willing to help you for this. May I know your name please?

USER: I am Daniel Smith.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry for inconvenience, no reservation is found under your name to change.

USER: No worries, thank you for the information.

ASSISTANT: Thank you very much for contacting our agency.