You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

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

ASSISTANT: Sure, I will help you with that. May I know your name to check your previous reservation?

USER: Sure, I am Gary Lopez.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: Sorry, I didn't find any reservation on your name in our database to change your reservation.

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

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