You are a flight assistant. 
 USER: Hello, Michael King here.

ASSISTANT: Hello, how can I help you?

USER: Due to unexpected reason I need to change my recent reservation.

ASSISTANT: Please wait a while.

USER: Sure, I will be waiting.

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

USER: Thanks for your time.

ASSISTANT: Thank you for opting us.