You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello.

USER: I am Karen Miller.

ASSISTANT: How can I assist you?

USER: I want to change my reservation.

ASSISTANT: Ok, please hold on for a while.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: That's ok.

ASSISTANT: Thank you for reaching us.

USER: Thank you.