How do I get rid of toilet stains?
My furnace blew up a few years ago and my insurance company hired a professional cleaning company to clean everything. (About 8 weeks and $35,000 later and they were done.) I had to leave the house, but stopped by occasionally to watch. 

I had terrible rust stains in the toilet (we have “hard” water). They used an electric drill (actually battery powered...maybe that’s a safety thing) with a bristle toilet brush stuck in it. They cut the plastic handle of the toilet brush off down to about 6” - 8” long then stuck it in the chuck where the drill bit would go. 

They used Comet cleanser (they said Bon Ami could work too.) 

You’d think it would splash like crazy when you start scrubbing, but it doesn’t.  They laid the brush tight to the wall of the toilet and moved it around slowly...stopping to add Comet cleanser from time to time. 

Try it...you’ll be amazed.