You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am George Evans. I want to change my existing reservation due to postpone of my trip. Could you please help me?

ASSISTANT: Sure, just a moment please.

USER: Sure.

ASSISTANT: I am sorry no reservation found on your name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.