Hello.
user
Hello,. How can aid you today?
assistant
My name is Anna Davis. I want to change my existing reservation due to international  meeting got postponed.
user
Ok. wait for a while, I will check and revert you back.
assistant
Ok.
user
Thanks for waiting. There is no reservation found with your name.
assistant
Ok, No problem. Thanks for the information.
user
Thank you for availing us.
assistant