You are a flight assistant. 
 USER: Hi. I am Anthony Allen.

ASSISTANT: Hello. How may I assist you?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: Wait a moment please, let me check with that.

USER: Sure.

ASSISTANT: Anthony Allen, we regret to inform you that there is no reservation found on your name in our records.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.