You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Robert Miller.

ASSISTANT: How may I assist you?

USER: I need to change my existing reservation, can you please help me out?

ASSISTANT: Sure, I am here to help you out. Robert Miller, we regret to inform you that there is no reservation found on your name in our records.

USER: That's ok, thank you for searching the details.

ASSISTANT: Thank you for reaching us.