You are a flight assistant. 
 USER: Hello, I'm Laura Thomas.

ASSISTANT: Hello,. How may I assist you ?

USER: I was informed by a receptionist, That there is a change of dates in my already scheduled appointment with the surgeon. So, I would like to cancel my existing reservation. Can you please, Help?

ASSISTANT: Please wait for a while. Sorry, there is no reservation.

USER: OK.

ASSISTANT: Thanks.

USER: Thank you, For providing the information.

ASSISTANT: Have a nice day !.