Hello.
Hello. How may I assist you?
I want to change my existing reservation. Could you help me with that?
Sure, I will help you.
Thank you.
May I know your name?
Amy Wilson here.
Please, wait for a while.
Ok.
Thanks for waiting. I am sorry to inform you that, there is no reservation found  on your name.
That's ok, no problem. Thank you.
Thank you for approaching us.