You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Please change my existing reservation due to some health issues?

ASSISTANT: May I know your name please?

USER: Sure, I am Kenneth Walker.

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Most welcome.