You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my existing reservation due to postpone of my live concert at Orlando. Could you please help me?

ASSISTANT: Ok, may I know your name in the meanwhile?

USER: I am Nancy Jackson.

ASSISTANT: Sorry, there is no reservation found under your name to change it. Thanks for consulting us, have a good day.

USER: No problem, thank you for the information.