You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, please share your good name?

USER: Sure, I am Brian Johnson.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thank you for your time, sorry no reservation found on your name.

USER: That's fine, thank you for your information.

ASSISTANT: Thank you for choosing us.