You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: William Davis this side, want to do some modifications in my existing reservation, can you help me?

ASSISTANT: Sure, hold on for a moment. Let me check. Sorry Davis, there are no flight reservation found on your name.

USER: Ok, no issues.

ASSISTANT: Thank you.

USER: Thank you for your information.