You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I assist you?

USER: Due to sudden change in my office meeting I need to cancel my existing reservation can you please help me out with the change.

ASSISTANT: Please provide your name?

USER: I am Rachel Wilson. actually I need to change my existing reservation.

ASSISTANT: Ok. No reservation found. Thanks.

USER: Thank you, so much for your service.