Hello.
Hello, how may I serve you at this moment?
I would like to change my existing reservation, which is done recently. Can you please help me out?
Sure, we are here to help you.
Thank you for considering my request.
May I know your name to check your reservation status?
Sure, myself Rebecca Baker.
Thank you for waiting.
Ok.
Sorry, there are no reservation found with your name in our records.
Not a problem, anyway thank you for the information.
Thank you for choosing us with a query.  We hope to serve you again. Have a nice day.