Hi, I am Margaret Campbell.
user
Hello, how can I assist you?
assistant
My business trip has been changed to Dallas, can you please help me in changing my existing reservation?
user
Please wait for a while, I will check and revert you.
assistant
Ok.
user
Sorry,there is  no reservation found on your name.
assistant
Ok, thank you.
user
Thank you for availing us. Have a wonderful day.
assistant