We have an old Eljer Bathrub faucet with diverter that I can't remove from the wall and appears to be seized up. It is not the slip on type and has some sort of screw on assembly. When i attempt to rotate the faucet counter clockwise both the hot and cold water handles try to rotate as tension forms on the pipes.

Any thoughts on how to remove this faucet? The only reason we need to d anything is because the diverter washers are incompetent now and the shower has no pressure.

The house is for sale so this is a minimal repair fix needed here.