You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you?

USER: Due to some personal problems, I would like to change my existing reservation. Can you help me?

ASSISTANT: Sure, I can help you with that. Can I know your name for that?

USER: My name is William Evans.

ASSISTANT: Give me a moment.

USER: Ok.

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

USER: That's fine. Thank you for the information.

ASSISTANT: You are most welcome.