My 1980s house has one piece fiberglass shower/tub combinations in both bathrooms. They have faucets for hot, cold, and the shower diverter. I have replaced (numerous times)the stems, "o" rings, seats and still have problems with the diverter completely diverting the water and the even flow of hot and cold water. Is there a way to cut out a section of the shower wall...put in a single faucet design and cover up the hole. Even my plumber scratched his head on this one. Note: The house is on a slab and the bathrooms are back to back...though offset slightly.