So I had a bathtub with three faucet control and the hot would not shut off. Pulled of the handle and found behind it a plastic piece had broken and was preventing it from shutting off.
See picture.
I pulled the pieces out and was able to turn it off, but there was no stop so one had to turn it till you found the sweet spot to turn it off... Could not find it in a local hardware store, so I made my version of it and printed it out. I have no idea the brand of these faucets. Not marked except Hot, Cold, and the diverter (^).

Eureka, it worked!!!