I am truly amazed that the message isn’t getting out. If someone calls you out of the blue and says that your computer has been hacked, why would you take them seriously? If you are browsing the web and suddenly your screen is filled with this ugly message telling you that you have been hacked, why oh why would you call the number on the screen, and why would you pay the folks at that number anything in hopes of correcting the problem?
Just a touch of common sense folks, the message on your screen has been caused by some type of malware. Therefore, any information contained in that message should never be trusted. Microsoft will never call you, certainly not to tell you that you have been hacked or that you are sending spam, or anything else. It isn’t just Microsoft either, Symantec and a whole raft of other security companies are in the same boat, they rarely have a means of tying an issue on your computer to your phone number (unless they are illegally snooping around in your computer, which means they aren’t a trust-able entity) and with rare exceptions, they simply have no way of knowing that your computer is involved in anything let alone being hacked; but, the hackers do know and have no compunction against using what they can learn to get money, and lots of it out of you.
With Windows 10 and the latest versions of MacOS, you can get a situation where your browser posts up an inappropriate page with instructions, phone numbers, etc. In all cases, ignore any instructions on that page / screen. Best practices dictate calling your favorite help line, technician, or consultant who probably sees the same screen several times a week (people, generally, only call me if there is a problem) and has practice defeating the hack before it can do any real damage. The hope is to catch the would-be infection before it can get the chance to become part of your operating system (OS); while it is still just in the browser, the potential for damage to your system, your files, your personal information is quite small.
With the current browsers, it can be reasonably straight forward to remove any and all recent changes to the browser and get you back safely surfing again. It is my hope that no single user would encounter this kind of issue themselves regularly enough to get good at correcting this kind of issue; but, trust me, those of us who provide service and support do get enough practice.