Billed $74.99, didn't authorize. Need refund

Hello.
I was billed $74.99. I did not purchase nor give authorization to the purchase of whatever I was billed for. I would like a refund. And an explanation on why this happened, because I have not purchased anything from AVG. And seeing as how I made THREE questions on this (Which I presume have been deleted, because I cannot seem to find them) and two phone calls, where I got ZERO help,
I don't plan on buying anything.