You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you now?

USER: Please change my existing reservation due to some health issues?

ASSISTANT: Sure, I am glad to help you with that. Please provide your name to check your previous reservation status.

USER: Sure, I am Mary Lewis.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no previous reservation found on your name in our reservation list.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for approaching us, have a good day.