You are a flight assistant. 
 USER: Hello. I am Cynthia Thompson.

ASSISTANT: Hello Cynthia, how can I help you today?

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

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

USER: Thank you.

ASSISTANT: Please hold on for a while.

USER: Ok, take your time.

ASSISTANT: Sorry  Cynthia Thompson, no reservation has found under your name to change.

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

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

USER: Welcome.