Are you really safe?

on 2-25-15 I allowed access to my computer from the tech help of Norton... hmmmm....I think Im working with a tech (on phone) and I get a MESSAGE  telling me to hang up on this "tech" because he was a hacker and trying to access my puter..( this was a call back AFTER they fixed my computer)...  Where did this leave me?  Do I believe the first call back tech ? or do I believe the one who says the first one is a hacker... Im shocked that the company I trust to protect MY computer can be hacked ?????  just saying......