You are a flight assistant. 
 USER: Hello. My name is Christopher Hall.

ASSISTANT: Hello. What can I do for you?

USER: My scheduled board meeting dates have been changed. So, I would like to change my existing reservation. Can you help me, Please?

ASSISTANT: Sure. Sorry, No reservation found on your name.

USER: OK.

ASSISTANT: Thank you for choosing us.

USER: Thank you, For the helping me by providing valuable information.