You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

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

ASSISTANT: Sure, may I know your name to check previous reservation.

USER: Sure, I am Richard Hernandez.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no active reservations on your given name to change.

USER: It's ok, thank you.

ASSISTANT: Thank you for reaching our service.