You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: My name is Nicholas Mitchell. Due to a sudden meeting, my trip is postponed. Could you help me in changing the reservation?

ASSISTANT: Ok, please hold on for a moment. Sorry, there is no reservation found.

USER: That's ok.

ASSISTANT: Thank you, have a good day.

USER: Thank you for your time.