You are a flight assistant. 
 USER: Hello, I am Nicholas Edwards.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my exiting reservation.

ASSISTANT: Sure.

USER: OK.

ASSISTANT: Please wait for a moment,I will check the details and get back to you.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation on your given details.

USER: OK. Thank you for the information.