We believe our bathroom was last remodeled in the 1930's. The shower/tub has four handles: H&C for shower and H&C for bath. The shower faucet has become nearly impossible to turn off and can't be used, and the others move only with great effort. A neighbor who is a contractor took a look and said he believes the worst faucet handle is stripped, and the handles are so old they can't be replaced, because the whole assembly is a different size than is used today. In fact he'd never seen a 4-faucet handle set up before.

I spoke to a plumber friend who guessed that we might need to break out the wall and redo all the plumbing behind it and that will be a big expense.

Is there any way we can somehow replace the faucet assembly (not sure my terminology is correct here), maybe find plumbing parts that would fit, without tearing down the wall and replacing the pipes etc? There have been no leaks and as far as we know the pipes are in good condition.

Also, are there plumbers who specialize in repairing plumbing in old homes?
Thanks for any advice.