Leaking Diverter - Can't remove

When I turn on my shower, water still runs out of my bath tub faucet. Because of this, I'm trying to replace the diverter on my shower - it is it's own fixture (ie, there is a hot water handle, a cold water handle and a seperate diverter). The faucet is a Gerber faucet. I have purchased a stem removal wrench and I cannot budge the item. I'm turning the stem counter clockwise but I cannot seem to get the thing out of the wall. I've already purchased a replacement stem but I can't use it because I can't get the old diverter out of the wall. Any ideas?

diverter

Either a bigger wrench or the correct one. I have never had a diverter that would not unscrew given the proper incentive.

Diverter

Good advise. I was able to use a large cresent wrench to get more leverage and did remove it.

Stem Removal

Stems are best removed with the correct plumbing socket and a large crescent wrench for leverage. Really stuck ones may require a cheater bar and possibly PB blaster if there's evidence of corrosion.