You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Frank Anderson.

ASSISTANT: Wait a moment please.

USER: Sure.

ASSISTANT: Frank Anderson, we haven't found any reservation under your name in our database.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you for choosing us.