over tightened oil filter cap

This may sound a little dumb but bear with me. Have you tried the correct size oil filter wrench? The only other thing that I have done in the past is poke a hole in the filter body itself with a screwdriver and use the screwdriver as a pry bar to loosen the filter. Try to use a screwdriver that has a square shaft so that you can use the flat part of the shaft against the filter body. This will help minimize the possibility of tearing the metal on the outside of the filter. Other than that I would call the local dealer or repair shop and ask them what they suggest.