You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Samuel Lewis. I want to change my existing reservation due to postpone of my seminar. Could you please help me?

ASSISTANT: Yes, I can help you. Give me a moment.

USER: Sure.

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

USER: No worries, thank you for the information.

ASSISTANT: Thank you for contacting us.