You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Could you please change my existing reservation due to postpone of my trip?

ASSISTANT: Sure, may I know your name?

USER: I am Stephen Scott.

ASSISTANT: Please wait a second.

USER: Sure.

ASSISTANT: Sorry, no reservation found on your name.

USER: No problem, thank you.

ASSISTANT: Thank you for opting us.