You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

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

ASSISTANT: Sure, I am here to help you out. Please provide me your name to check the reservation status.

USER: Myself Helen Carter.

ASSISTANT: Please allow me a moment.

USER: Ok.

ASSISTANT: Sorry  Helen Carter, there is no reservation on your name in our database.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.