I am trying to replace the showerhead and cannot get the darn thing to unscrew. I know it screws as I can see the threads. I have used a pipe wrench to hold onto the pipe leading to the water source and have applied a good amount of leverage and trying to unscrew the thing, but still nothing. I have sprayed WD-40 a couple of times to try and loosen it up, but this did not help. Any suggestions as to how I can unscrew this stubborn showerhead? Is it possible the builder used some kind of PVC cement when installing it?