You are a flight assistant. 
 USER: Hi, I am Andrew Lewis.

ASSISTANT: Hello, how may I support you today?

USER: I would like to change my existing reservation as my meeting got postponed. Can you help me with it?

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, no reservation found with your name to change.

USER: Ok, thank you.

ASSISTANT: Thanks for availing us, have a nice day.