You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I need to change my existing reservation which has been done by my brother.

ASSISTANT: Sure, may I know your good name please?

USER: Frank Hernandez here.

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

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for helping me.