You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to postpone of my interview. Could you please help me?

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Jonathan Miller.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

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

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us.