Hello.
user
Hello, how can I help you today?
assistant
I need to change my existing reservation for some personal reason. Can you  please change my reservation?
user
Sure, please wait for a moment.
assistant
Ok.
user
Thanks for waiting, sorry there is no any reservation found on your name. May I know your name?
assistant
Joshua Phillips is my name.
user
Thank you, have a nice day.
assistant