I signed up for a year but decided not to renew when the store was down on so many weekends. The auto renew feature was well hidden so I didn’t know it was turned on. Anyway, they renewed me for another year. I called to have it reversed, figuring any company with good customer service would do that. No go. They refused to refund the money. I disputed it with my credit card company. Guess what Sony did? They froze my PlayStation account! I can’t get into the games I paid for. I even called the bank to reverse the dispute two months ago but still nothing. Just an FYI—Sony likes to play hard ball. They do not seem to be customer focused. Keep that in mind when dealing with them. Protect yourself and turn off auto renew.
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While I'm not sure if it is documented in T&Cs; Sony will disable, or ban your PSN account, if you dispute a PSN transaction. It is however documented in the Terms of Service that PS+ will automatically renew, which is pretty standard fare for any subscription service - digital or print.
I think your only recourse is to call Sony again, and ask what has to be done to put your account in good standing.
I would say welcome to the PS Community, but it sounds like you will not be back.
Or a sure way of preventing such things from happening is to just remove your Credit Card altogether and only add it when you need to buy something. Or better yet, just use the Pre-Paid PSN cards.