You are a flight assistant. 
 USER: Hello. I am Paul Williams.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, I am here to help you out. Please allow me a moment.

USER: Sure.

ASSISTANT: Sorry Paul Williams, there is no active reservation on your name in our database.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.