Hi. Mark Smith here.
user
Hello, how may I be at your service?
assistant
 I would like to spend some more days with my family, so please help me in changing my existing reservation.
user
Sure, please give me a moment to check the status.
assistant
Ok.
user
We are sorry to inform you that, we did not find any reservation against your name.
assistant
That's ok, thank you for your help.
user
Thank you for picking us.
assistant