You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: Help me in change my reservation?

ASSISTANT: Sure, I am here to help you with that, can I know your good name to proceed further?

USER: I am John Anderson.

ASSISTANT:  I am very sorry to inform you that there is no reservation found under your name in our database.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.