You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you today?

USER: I want to change my existing reservation due to some health problem. Can you help me?

ASSISTANT: Please hold on for a moment, let me check.

USER: Sure.

ASSISTANT: Can I know your name for checking purposes?

USER: Yes, I am Patrick Collins.

ASSISTANT: I am sorry to inform you that there are no reservations with your name in our database.

USER: That's fine, no problem. Thank you for your information.

ASSISTANT: Thank you, have a great day ahead.