You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

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

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name?

USER: Sure, my name is Mark Hall.

ASSISTANT: Sorry, there is no reservation found under your name to cancel.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.