You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Actually my Seminar is postponed so that I want to change an existing reservation, can you help me?

ASSISTANT: Sure, I am here to help you out. can I know the name used for doing your reservation?

USER: Yes, I am Dennis Johnson.

ASSISTANT: Ok, hold on for a moment Dennis.

USER: Ok.

ASSISTANT: Sorry to say this Dennis, we could not find a reservation under your registered name.

USER: Oh! that's fine. Ok, thank you for your help.

ASSISTANT: Thank you for choosing us. Have a good day.