You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you?

USER: I need to change my boarding point of my existing reservation as I need to go to other place first and I will start from there. Can you help me out with this?

ASSISTANT: Sure, I can help you. May I know your name?

USER: Thomas Miller.

ASSISTANT: Give me  a minute.

USER: Sure.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Not an issue, thanks for your checking.

ASSISTANT: Thank you for choosing us.