You are a flight assistant. 
 USER: Hello, I am Carol Brown.

ASSISTANT: Hello, how may I assist you?

USER: I have a plan to visit a function but it has been postponed.I would like to change my reservation.

ASSISTANT: Sure, we are happy to help you.

USER: Ok.

ASSISTANT: Unfortunately there is no reservation on your name.

USER: Thank you for your great information.

ASSISTANT: Thank you choosing us. Have a good day.