You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please change my existing reservation as my plan to go for holiday trip got postponed?

ASSISTANT: May I know your name please?

USER: I am Michael Miller.

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

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for opting us.