You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I aid you today?

USER: My name is Ryan Lee, my business trip was postponed, so I want to change my existing reservation.

ASSISTANT: Sure, wait for a while,I will check and inform you.

USER: Ok sure.

ASSISTANT: Thank you for being patience, sorry to inform you that there is no reservation on your name.

USER: Ok, thanks for your service.

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