You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Can you please help me in changing my existing reservation? As my meeting got postponed at New York.

ASSISTANT: Sure, can I know your name please?

USER: My previous reservation has done with the name Paul Williams.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

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

USER: Oh! That seems something went wrong while booking the ticket previously.

ASSISTANT: Thank you for approaching us.

USER: Anyways, thank you for providing information.