You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Stephen Anderson.

ASSISTANT: How may I assist you at this moment?

USER: I want to change my reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok, take your time.

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

USER: That's ok, no problem. Anyway thank you for checking.

ASSISTANT: Thank you for reaching us, have a great day.