You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I am Karen Phillips. Can please change my existing reservation?

ASSISTANT: Sure, I am here to help you. please wait a second.

USER: Ok.

ASSISTANT: There is no reservation found under your name to change.

USER: Ok, not a problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.