You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you at this moment?

USER: I want to change my existing reservation due to bad health issues.

ASSISTANT: Sure, we are here to help you with this.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I am Anna Clark.

ASSISTANT: Please hold for a while, let me check your previous reservation status.

USER: Sure.

ASSISTANT: Thank you for waiting. There is no active reservation found with your name in our database to change it.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for reaching us, have a great day.