You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I want to change my existing reservation due to sudden postpone of  client meeting. Can you help me in doing that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Can I know your name to check your previous reservation?

USER: I am Anthony Collins.

ASSISTANT: Please wait a moment to check.

USER: Sure.

ASSISTANT: We regret to inform you that there is no reservation found on your name in our records.

USER: Ok, no issues. Thank you.

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