Plastic Tile Deteriorating

We're not the ones that installed it, and I wouldn't recommend this stuff to anybody. There's a soft spot in our tub surround, where it meets the tub. The surround is that fake plastic stuff, that's all one sheet, and has lines on it to look like tiles. In reality, it just looks like crap, I don't think anyone would be fooled. We're not ready to redo the bathroom at the moment. We want to ditch the arcrylic tub as well, and pretty much need to tear it down to the studs. So that means I have to buy a sheet of this plastic tile, to replace the sheet that is melting at the bottom. I don't really want to buy this garbage, but we don't really have a choice, there doesn't seem to be any other way to repair it. So we're using the basement shower for the time being. I need to rent a van on the weekend, so when I'm picking up drywall for the basement, I'll pick up a sheet of this garbage, and install it properly, so that it lasts more than 4 years, which is when I think the previous owner did the bathroom. He didn't put enough silicone at the bottom of the sheet, where it meets the tub, so the masonite, or paper, or whatever the backing is, soaked up water (capillary action) and evenually turned to mush. That's why you shouldn't use this stuff in the first place.