You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you at this moment?

USER: I want to change my existing reservation, can you please help me out?

ASSISTANT: Sure, I am very happy to help you with that.

USER: Thank you.

ASSISTANT: May I know your name please.

USER: My name is Samuel White.

ASSISTANT: Sorry, no reservation is found on your name in our database.

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

ASSISTANT: Thank you for reaching us.