You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you at this moment?

USER: I want to change my existing reservation due to some official meeting.

ASSISTANT: Sure, I am here to help you with that. Ok, wait for a minute. May I know your name?

USER: Sure, Donna Lee here.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for approaching us.