I am interested in the best option to transform a tub into a useable shower. The walls above the tub are not waterproff. I have looked at several methods; ceramic tile, 3 piece wall systems, etc. I am concerned about water leakage with the surround wall systems..... ceramic tile is too costly for me. What surround wall system is cost friendly and reliable? Any suggestions? Also, I have seen an ad for Re-Bath of Illinois. Has anyone had experience with this company?