You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you help me?

ASSISTANT: Sure, I am gleeful to help you with that. May I know your name please?

USER: Lisa Hernandez here.

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

USER: Sure.

ASSISTANT: Thank you for waiting, but I am very sorry to say that, there is no active reservation found on your name in our database to change it.

USER: No problem, Thanks for the information.

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