I've had problems with hens going broody, too. It use to drive me crazy, thinking they were going to die if they just sat forever. I would remove the eggs, dunk in cold water, remove hen from nest etc. nothing ever worked. Now, I have two that go broody often. I just let them sit and after about three months, they give up for awhile, then go back to being broody.
I did buy one chicks a couple times. I would let her sit for a couple weeks, then chase her off the nest, take the eggs, crack one or two, leave the broken shells, and then put the babies there for her to find when she came back. Worked every time!
A couple other times, I got fertilized eggs from a friend, and let her hatch them, she loved being a mama.