You are a flight assistant. 
 USER: Hi, I am Janet Lee.

ASSISTANT: Hello, how may I support you?

USER: Due to some emergency work, I need to change my existing reservation. Can you help with that?

ASSISTANT: Please wait a moment, let me check and return to you.

USER: Sure.

ASSISTANT: We are very sorry to inform you that there is no reservation found on your given name.

USER: OK, thanks for information.

ASSISTANT: Thank you for choosing us.