You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I want to change my existing reservation, my music concert got postponed. Can you please help me out with that?

ASSISTANT: Sure, may I know your name?

USER: Ok, I have reserved it on the name of Mark Wilson.

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

USER: Oh! I think the ticket was not booked due to server issue.

ASSISTANT: Thank you.

USER: Anyway, thank you for checking.