For the third time I have a hole in the pipe below my shower pan. Twice I've had it fixed by two different people. They both had to remove the lower tiles, the shower pan and replace. Ok, so I am done with having someone else do it wrong. I can figure out how to remove everything but the cement/concrete shower pan. How do I go about removing that? I am not a huge person. What do the professionals use? Any clues on why this keeps happening?