The seal of disapproval

We recently had our en suite fitted out with Showerwall shower-lining panels, which we specified on the basis of the company’s sales brochure. A few weeks after the Showerwall was fitted, we noticed swelling on the bottom edges of the panels. I made a complaint and the manufacturer’s representative came to investigate. His report basically said the Showerwall was not sealed well enough with? silicone sealant.
We had read the Showerwall brochure, which uses phrases such as, “waterproof panelling”, “non-porous surface”, “Showerwall comes with a 15-year guarantee that’s as watertight as the panelling itself”. I maintain that without those words and phrases, we would not have chosen this product. To have such an integral part of the structure of a bathroom wholly dependent on silicone sealant, even to a layman like me, seems ridiculous.
I believe their marketing is misleading. I called the company to state my feelings and they drew my attention to the phrase, “waterproof panelling system” (which occurs just twice in the brochure), meaning that from that I should have deduced that the panels themselves are not waterproof.