The requested URL was rejected. Please consult with your administrator. Your support ID is: 1191251132006548395.
I would try a Dremel type tool with an abrasive cutoff wheel. Of course you need to be careful of the porcelain. I've cut many screws and bolts this way. If you can't cut the bolt, you may be able to cut the nut, in the direction of the bolt's axis, then pry the nut apart at the cut line.