Bedsquare and it's "20 year warranty"

Today I went to bedsquare in Ottery at the hyper where +/- two years ago I bought an orthopedic mattress. I knew that they advertise a 20 year warranty and I tried to enquire about it in-store. The "helpful" salesman immediately blamed the failure of the mattress on my weight. I weighed 112kgs then and still do. Then he asked if the mattress was clean and when I said well it's not spotless he immediately rep**** with: If it wasn't filthy we could take it back and offer you something else if you paid a little extra. I turned on my heels and said no thanx it's fine I'll shop somewhere else and as I walked out he shouted: We're trying to help you! I don't know where bedsquare found this ***** but they've definitely lost a customer and a recommendation due to his lack of profesionalism. Also if the 20 year warranty depends on whether I am able to keep the mattress spotless condition after two years of use I feel that this should have been communicated to me before I was duped into buying it.