You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Jeffrey Brown. I would like to change my existing reservation.

ASSISTANT: Sure, please hold on.

USER: Ok, please take your time.

ASSISTANT: Sorry, no reservation found on given name.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.