Step one in cases like this is to never accept any terms that include an automatic charge to your credit card. It's too late for that, it seems. You could call your credit card company and have them decline payment to mcaffee. I had McAffee years ago and recall that there is a deeply buried way of contacting them in an inconvenient manner, but it did seem to be possible.
Start doing some google and bing searches on this. Surely someone has figured it out.
My thoughts on McAffee? They can go to hell, those b.s.a.rds. That was the most vile and invasive piece of s..t software I have ever seen, and I hope everyone who works for them or sells it goes to hell after dying a horrible and painful lingering death. In other words, I can empathize with you on this issue.