You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me to change my existing reservation?

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

USER: Myself Samuel Mitchell.

ASSISTANT: Sorry, there is no active reservation on your name in our records.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.