[quote name='Kazaganthi']The only thing I can think of is one cancels auto CC charge, and the other stops PSN Wallet withdrawal. It is stupid, I agree.[/QUOTE]
It is confusing. I think it's like this:
The Automatic Wallet funding is for when you have a credit card on file and don't have the proper amount for something already in your PSN wallet. If you have that "feature" on, it'll just take whatever extra it needs from your credit card (up to a certain amount). So when you stop that service it simply won't let you check out if you don't have the proper amount in your PSN wallet until you add more.
So you should be able to stop the auto renewal of PS+, and still leave the automatic funding feature on and it should not charge you for PS+ again as long as you have set auto renewal to off.
I think either some people forget to turn off auto renewal of PS+ altogether, or they turn off automatic (wallet) funding instead of automatic (PS+) renewal, in which case you would still be charged for PS+ once your sub expires.