Our shower faucet is leaking, and all I need to do is replace a rubber washer inside the handle. Unfortunately the shower handle is stuck (I can’t unscrew it). We had a couple plumbers come out and tell us they’ll need to cut a big hole in the fiberglass shower kit, replace the shower handle, then put a big sheet of metal over the hole… that’s going to hurt the resale value!

I asked about coming in from behind the shower, but we live in a condo and would have to rip out our kitchen cabinets (which are on the other side of the bathroom wall).

I’m trying to loosen the shower handle threads with Liquid Wrench, but is there another way to fix the leak? I have a hard time believing this idea of cutting a huge hole then using a big sheet of metal as a patch is the only way.
Thanks for the help! It’s a single handle, here’s a picture:

http://www.hardwarestore.com/pop-print/larger-image.aspx?prodNo=3744

I would LOVE some more help with this. My understanding is in order to replace the rubber gasket that’s causing the leak, I need to unscrew the cap behind the shower handle. Is there another way?
EDIT: That bonnet is the part that’s stuck. The plumbers that came out said they didn’t want to try to hard, because it could break (exactly what you said). I’m dousing it with Liquid Wrench right now to see if that will help loosen the bonnet, but I’m a little worried about trying to get it off. If I break it, I’m screwed!

If I can’t get it off, is the only option to cut a big hole in the fiberglass? That would suck.

i have a 1/2 bathroom that has a sink that is almost impossible to work under. I can’t get a wrench up there but i can use my hands. unfortunately, the bolt that tightens the faucet to the sink snuggly is under the sink and not turning. It moves up and down but then stops moving at a certain point. I assume there is dirt build-up and have tried using liquid wrench to no success. should i cut the pipe that goes through the sink hole or are there any other tricks? this sink is one where there is the water spout in the center, and then the hot and cold knobs are separate. any thoughts would be great.