You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Samuel Evans. Could you please change my existing reservation due to postpone of my event.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: No worries, thak you for the information.

ASSISTANT: Thank you for opting us.