Poor after sales service

I bought the 3-in-1 foam roller and absolutely loved it, so much so that I recommended it to my running friends. I ended up buying another 5 of them only for the inner plastic on two of them to break around 4 months later. After querying it, it took a while for anyone to get back to me. Eventually someone did and advised that the warranty is only for 3 months on them and therefore they can't replace but could offer me a 10% discount on a new one. Do I now have to buy a discounted roller every 4 months? Surely there's something wrong with the item for 2 of them to break?