You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to do some changes in my existing reservation, can you help me for that?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Larry King.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

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

ASSISTANT: Thank you for opting us.

USER: Welcome.