Not sure if that helps but I had problems paying as well a couple of months ago. However even though I was not able to pay directly for the reneval I was able to buy those deviant points you can use as internal currency. So I just bought the points and paid the reneval with them. For some reason that worked fine.
Couldn't by the points either, still gave me the same autobill error I can always try again now that the sale is over, but it really doesnt seem to like either of my credit cards
Weird that they have so much trouble with their payment system. I would have thought making sure people can buy their stuff would be Deviantart's first priority.