Over the weekend I attempted to replace the hot valve stem in one of my bathrooms and broke the large bronze piece that holds the threaded rod. I had to use a Dremel to cut out the threads that were left in the valve assembly to replace the stem. The only option I had was to remove the tile around the hole to gain sufficient access to the valve assembly. When I started to remove the tile I used a Dremel accessory and took care not to damage the material behind the tile or the surrounding tiles. However, as I was pulling the cut pieces out I basically blew out the plaster and chicken wire wall behind it. I now have a perfect 4"x4" hole with clean edges around the stem. The wall the tile is attached to is made of fairly decayed plaster and chicken wire and I know that my options are limited. What is the best method for fixing this at the least possible expense and time? I can gain access to the back side through a closet which would require me to cut through the drywall, but repairing a hole in the drywall would probably be a lot easier than fixing the hole in the shower. I could use any helpful advice anyone could give me. Thanks in advance.