You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I assist you?

USER: My name is Benjamin Williams.

ASSISTANT: Ok.

USER: I need my existing reservation to get changed.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no reservation found with your name.

USER: Thanks for the assistance.

ASSISTANT: Thank you for opting us.