You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: My name is Christopher Nelson.

ASSISTANT: Ok.

USER: Could you please help me to change my existing reservation?

ASSISTANT: Sure, I will help you with that. Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry for the inconvenience, there is no reservation found on your name.

USER: That's ok.

ASSISTANT: Thank you for approaching us.

USER: Thank you for the information.