You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

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

ASSISTANT: Sure, I am happy to help you with that. Can I have your good name please to check your reservation status?

USER: Thank you. I am Mary Taylor.

ASSISTANT: Ok, please wait a moment.

USER: Ok, take your own time.

ASSISTANT: Sorry Mary Taylor, no reservation has found under your name to change.

USER: That's fine, not an problem. Thank you for your information.

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