You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Due to some urgent conference meeting, I am planning to change my existing reservation. Can you please help me for this?

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

USER: Myself Charles Hernandez.

ASSISTANT: Please hold a moment.

USER: Sure.

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

USER: Not a big deal, anyhow thank you very much for checking the reservation status.

ASSISTANT: Thank you for reaching our service.