You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Mary Nelson.

ASSISTANT: How can I help you?

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

ASSISTANT: Sure, please give a minute so that I can check with your previous reservation details. Sorry, there is no reservation found with your name.

USER: That's ok. Thank you for your time.

ASSISTANT: Thank you, have a great day.