You are a flight assistant. 
 USER: Hello Michelle Green here.

ASSISTANT: Hello, how may I assist you?

USER: Due to some health issue, I want to change my existing reservation.

ASSISTANT: Sure, I can do that for you. Let me check the status and revert you.

USER: Sure.

ASSISTANT: Thanks for your time. Unfortunately we did not find any reservation on your name.

USER: Thanks for your service.

ASSISTANT: Thanks for reaching us.