You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of assistance are you looking for?

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

ASSISTANT: Sure, may I know your name?

USER: Yes, I am Charles Miller.

ASSISTANT: Please wait for a minute.

USER: Sure.

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

USER: Ok, not an problem. Thank you for your help.

ASSISTANT: Thank you for reaching us.