You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I serve you today? May I know your good name?

USER: My name is Dorothy Clark. My business trip is postponed, I want to change my existing reservation.

ASSISTANT: OK, Please wait for a moment while I check and get back to you.

USER: OK.

ASSISTANT: Thank you for waiting, we did not find any reservation.

USER: Thank you, for good service.

ASSISTANT: Thank you, Have a good day.