Hacked while using Norton internet security uptodate

I had Norton internet security 2015 current and fully upto date. I was hacked. The caller said they were from dell computer and they had my computer ID and some of my programs were not up to date. I stupidly let them look at my computer and they showed my financial information that was on my computer that they said Russian hackers were getting. They tried to scam me out of some money to fix my computer. They uninstalled Norton and put a bunch of free software on my computer and I don't know what personal information they took off my computer. I did not have credit card numbers or bank numbers in my computer so I'm too worried. Although I did get new credit cards and talked to my bank. I called Dell and they said they never call customers with download problems. Just wanted to know if anyone else had this problem and how did they get past Norton?????