Hi.
user
Hello, how can I assist you?
assistant
 I want to change an existing reservation due to my meeting got preponed. Can you change my existing reservation?
user
Sure, may I know your name?
assistant
Catherine Adams is my name.
user
Sorry, there is no existing reservation found on your name.
assistant
Ok, not an issue. Thank you for the quick response without delay.
user
Thank you for choosing us, have a nice day.
assistant