Spamhaus Agent 2.0.8 Virus has taken over my computer. No protection from Norton 2013

I would like to know why Nortor Anitvirus 2013 which I just purchase about 2 weeks ago and was live updated this morning DID NOT PROTECT MY COMPUTER?  I have a Dell Inspiron 15 with Win 8,  Today while surfing the internet I got a virus calling itself Spamhaus Agent 2.0.8 that took control of my computer.  It said that if I did not go to one of their advertised retail outlets (KMart, CVS Drugs, Mejiers) and purchase a Green Dot money card and enter the pin number on their web page that my computer file would all be corrupted.  I was able to run a Nortor virus scan while this thing was up to no avail.  When rebooting, the screen just came up again.  You could not close the window but for a few seconds.

 

I ended up calling Dell support for help since the computer is only a few months old.  It cost me $129 to have the tech tell me how to handle the problem.  What we did was a PC Refresh.  The tech told me that all my data would be okay.  However, my files were all corrupted, probably by the virus.  I did have back up from a few weeks ago, however all the programs I added since purchasing the computer were gone.  The Dell tech claimed the virus was in the computer registry.

 

So how come Nortor Anit Virus did not protect my computer.  Apparently I wasted $49 on this product.