You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you at this minute?

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: May I know your name?

USER: Sure, my name is Charles Smith.

ASSISTANT: Ok, please wait for a minute. Sorry to inform you that, there is no reservation found on your name in our database.

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

ASSISTANT: Thank you for consulting us.