You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I want to change my existing reservation, because of health issue. Can you please help me in this?

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Myself Amanda Davis here.

ASSISTANT: Sorry Amanda, there is no reservation found on your name.

USER: Ok, fine.

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

USER: Welcome.