if you want to sleep on a roller-coaster surface

Bought this from beautyrest guest program because of hard-to-find flippability feature. Have had decades of beautyrests for our large family bought through Macy's, and for the most part they were fine. This surface is so uneven as to be unsleepable, even before the sagging and edge collapse. Extra toppers etc. do nothing to even it out. Even flipped it, thinking that the underside might be flatter than the exposed side. Nope. Despite months of trying for a resolution with beautyrest, sending them phtos, credit card bill, mattress tags etc., they refuse to assist, telling me I haven't presented them with the "don't remove under penalty of law" tag, which like pillow tags, upholstery tags etc., no consumer who doesn't want their skin to scratch or sheets to tear, would leave on. What would you do in this case? PS I have never, ever posted an online review before.