Hi.
Hello, how can I assist you today?
Owing an emergence, I want to change my existing reservation. Can you please help me with it?
Sure, I will help you in changing your previous reservation. May I know your name?
My name is Anthony Edwards.
Please wait for a while.
Ok.
Sorry, no reservation found in our  reservation database.
Ok, no issues. Thanks for the help.
Thank you for approaching us, have a nice day.