You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, firstly may I know your name?

USER: I am Helen Wilson. I want to change my existing reservation, because my workshop in New York is postponed.

ASSISTANT: Ok, please give me a moment to find the existing reservation.

USER: Sure.

ASSISTANT: Based on your name I don't find any reservation on your name in our listing.

USER: It's ok, thanks for your information.

ASSISTANT: Thank you for reaching out here.Have a great day ahead.