You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your good name?

USER: My name is Charles Jackson.

ASSISTANT: Ok Charles, how may I help you?

USER: My meeting got preponed, so I would like to change an existing reservation.

ASSISTANT: Sure, I can help you in changing. Please wait a moment to check it. Sorry Charles, we cannot found any reservation based on your name.

USER: Its fine. Thank you for your assistance.

ASSISTANT: Thank you for approaching us Charles, have a nice day.