You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you?

USER: As my plan to go for shopping got preponed, I need your help in changing my earlier reservation.

ASSISTANT: Sure, I would be happy to help you. May I know your good name please?

USER: I am Donald Miller.

ASSISTANT: Ok, please wait for a while, I will check and revert you.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, no issue.

ASSISTANT: Thanks for opting us and have a great day.

USER: Thank you for the response.