You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to shift my planned dates to some other dates, please help me in changing my existing reservation.

ASSISTANT: Sure, may I know on whose name the ticket has been booked?

USER: My name is Katherine Lewis.

ASSISTANT: Sorry Lewis, there is no reservation found on given name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for communicating with us.