Infibeam.com — Delivering non functioning products and not replacing product

I bought two Stainless steel vaccuum flask-double walled from infibeam.com. When I tested it by pouring hot water, its not holding temperature for even 3 hrs. When i complained, they escaped stating I reported after 72 hrs, so they cant take up the complaint. I reported the second day I got the product. Courier people marked it as "delivered " when they got it on their hand, and not when they delivered it to me. Isin't the site responsible for delivering quality items to their customers? Don't they value other's money?