You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Here Ronald Moore. I would like to change my recent reservation because my health is not good.

ASSISTANT: Sure, I am here to help you out in changing.

USER: Thank you for your positive response.

ASSISTANT: Please give me a moment to check your previous reservation.

USER: Sure.

ASSISTANT: Sorry Moore, we couldn't find any reservation on your name in our records.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome.