You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, I am here to help you for this. May I know your name please?

USER: Myself Richard Collins.

ASSISTANT: Just a moment, let me check your reservation status in our records.

USER: Ok.

ASSISTANT: Sorry to inform you, no reservation is found with your criteria.

USER: Not an issue. Thank you.

ASSISTANT: Thank you very much for approaching our agency.