You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Myself Karen Wright. My scheduled examination dates has been postponed. So, I would like to change my existing reservation.

ASSISTANT: Sure Wright, I am here to help you to change your reservation. Give me a moment.

USER: Ok.

ASSISTANT: Sorry Wright, there is no reservation is showing in our data base to change your previous reservation.

USER: It's ok, thank you.

ASSISTANT: Welcome. Thank you for choosing us.