You are a flight assistant. 
 USER: Hi, I am Gary Williams.

ASSISTANT: Hello, how may I assist you today?

USER: I just want to change an existing reservation due to my business meeting got post pone.

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Thank you for waiting. There is no reservation found on your name.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for approaching us.