You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: This is Michelle Clark, can you help me to change my existing reservation?

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

USER: Thank you.

ASSISTANT: Wait a moment please.

USER: Sure.

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

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.