You are a flight assistant. 
 USER: Hello\.

ASSISTANT: Hello, what type of help you are looking from us?

USER: I am Ronald Green, I want to change my reservation which I have done long back.

ASSISTANT: Yes, I am here to help you about that.

USER: Thank you.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: It's ok, anyway thank you for the information.

ASSISTANT: Thank you for choosing us.