Could not check coverage of Norton Internet Security

Norton Internet Security for my Mac running latest El Capitan OS-X is not working.  I can not get Live Updates and the application can not validate itself with Symantec because background application is not running.

I have contacted tech support but they did not fix the problem.  The technician took control of my machine ran some utility and when I rebooted my Mac the hard drive was thrashed.  I spent 28 hours restoring from an archive.  Reinstalled Norton Internet Security with last NIS version from your website problem still exists.

I have been very happy with your product for many years on my Mac and PC.  Currently my Mac has El Capitan and your product is not working and at this point I am sorry to say fed-up and ready to get a refund for my subscription and install AVG.  Please tell me how I can resolve this issue so I can continue to be happy with Symantec.