You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Amy Lewis. I want to change an existing reservation, due to some health issue. Can you please change my reservation?

ASSISTANT: Sure Lewis, I am here to help you for that. Give me a moment.

USER: Sure.take your own time.

ASSISTANT: Sorry Lewis, there is no reservation found on your name to change your existing reservation.

USER: That's fine.

ASSISTANT: Ok.

USER: Thank you for your service.

ASSISTANT: Welcome. Thank you for choosing us.