Hi, I am Samantha Gonzalez.
Hello, how may I render you at this moment?
Owing an emergence, I want to change my existing reservation. Can you please help me with it?
Sure, I am here to help you. Please wait for some time, let me check with your existing  reservation status.
Ok.
There is no existing reservation found on your name in our data base.
No problem, thanks for the information.
Thank you for approaching us.