You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be a help for you?

USER: I'm Barbara Hall. My scheduled examination dates has been postponed. So, I would like to change my existing reservation which is under my name.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation active on your name to change.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Most welcome.