You are a flight assistant. 
 USER: Hello.

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

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

ASSISTANT: Sure, I will help you with that. Can you please mention your name for further process?

USER: I am Gregory Harris.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: There is no previous reservation available under your name.

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

ASSISTANT: Thank you for reaching us.