You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I guide you today?

USER: Due to the change in the venue of the event, I would like to change my existing reservation. Can you help me?

ASSISTANT: Please provide me your name.

USER: My name is Mark Nelson.

ASSISTANT: Please hold on a moment.

USER: Sure.

ASSISTANT: Sorry to say, there is no reservation found by your name.

USER: That's ok, thank you for the information.

ASSISTANT: Most welcome.