You have encountered relatively common dodge intended to induce you to spend a lot of money on un-needed repairs and malware in the guise of anti-malware software products. Not only will you be out the money you paid, the fraudsters will have all they need to max out your cr3edit card and get additional credit cards in your name, and the biggest insult will be the time and/or money you will spend getting rid of the malware you helped them install on your system.
While you may get a legitimate notification from the App Store or System Preferences > Software update notifying you of a software or OS update which may direct you to open the App Store or System Preferences > Software update, Apple notifications will never — ever — tell you to contact any person or entity by any means!.
