You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Myself Charles Robinson. I want to change my plan.I want to change my existing reservation.Can you please help me out?

ASSISTANT: Sure. Give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name. Thank you for choosing us.

USER: Ok, thank you.