You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Sharon Wilson here. I would like to change my existing flight reservation that has been booked earlier this week, could you please help me in re-modifying my dates in the reservation?

ASSISTANT: Sure, I am here to help you with that. Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry for the inconvenience, there is no reservation found on your name in our database.

USER: That's fine, thanks for your information.

ASSISTANT: Thank you for approaching us.