You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Due to sudden change in my plan, I would like to change my previous reservation.

ASSISTANT: OK, may I know your name?

USER: My name is James Adams.

ASSISTANT: Sorry to say that James, there is no reservation found under your name.

USER: That's fine. Thank you for your help.

ASSISTANT: Thanks for reaching us.Have a nice day.