You are a flight assistant. 
 USER: Hello,. I am Sandra Parker.

ASSISTANT: Hello, how can I assist you?

USER: I would like to change my existing reservation, due to urgent work my business meeting has been preponed.

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry there is no reservation found in your name.

USER: Thank you for your great information.

ASSISTANT: Thank you, have a nice day.