Why Did Norton Not Stop This Problem?

This is my first attempt to use the forums so I hope I am in the right place.  About 3 weeks ago I was on a web site that wanted to show me a video but it suggested that I update the Flash player version I had on my machine first.  I have an HP all in one running Windows 8.1 (64 bit).  So I clicked on the download button and I guess I was distracted because I assumed that it had taken me to the Adobe site so I clicked again on the download button that appeared.  Well, it turned out that I had been taken to some third party site and it seemed like almost instantly that my machine seized up and stopped. I noticed that I now had two new applications that I did not recognize-"PC Tech Hotline" and "Spy Clear" which I realized instantly were the problems in some way. I tried rebooting and the reboot worked normally except that once it was back to what appeared to be the normal starting point, nothing I clicked on would work.  I spent the next 8 days trying to get up and running again.  I was always able to restart and get back to my normal desktop but I could not get anything to work from that point. I could not get any professional help because I could not afford to pay for it.  I kept trying to get into safe mode but it just would not happen.  I tried running Norton but it would not run.   After many days a friend gave me about 8 pages of information on how to get into safe mode on a Windows 8.1 machine.  It took me 2 days to actually understand the instructions and get into safe mode.  This allowed me to first run Norton which detected and removed 37 issues but it did nothing to the two new apps.  In fact I got a message from the new PC Hot Line app that said "If there is ever any problems with your PC, call me and schedule an appointment to get help" which seemed a bit too coincidental to me.  At this point I was able to get into the control panel and uninstall the two new apps.  BINGO, I finally have control of my machine again and since then everything seems to be working as it should.

My question is why did Norton not stop these two "bad and nasty" apps from downloading onto my machine in the first place? They were obviously the problem since as soon as I was able to remove them, all was well again.  Also, I should have contacted Norton for help but I could not get into Norton to find the phone numbers etc.  Besides paying more attention in the first place, what should I have done to fix this problem in less than 8 full days of agony?

Thanks for any help you can give me.  Deacon Al