I received an email saying that I could download Norton 360 free. I assume ths would replace whatever version I have at the moment. BUT when I came to try it, they wanted all sorts of details about credit cards and so on.
If in fact this is a legitimate offer from Norton and you've previously turned off Auto-Renewal, I believe it will require reactivating Auto-Renewal to activate the upgrade. Hence why it would be asking for the credit card info. Once you've setup 360, you can turn off Auto-Renewal again and delete your credit card info.
However, please ensure the email was in fact from Norton first!