Hello.
Hello, how may I assist you today?
I would like to change my existing reservation, which is done recently recently. Can you please help me out?
Sure, may I know your name?
Thank you for considering my request. Myself Nicholas  Scott.
Ok, please wait.
Sure, I will wait.
Thank you for waiting, sorry as per your concern I can not change your reservation because there is no reservation found on your name.
That's ok, no problem.
Thank you for reaching us.