Sagging nightmare within 1 year.

Terrible sagging 1 year into ownership. Company would not honor the warranty because they claimed there weren't enough support feet in the bed frame. This is bologna, because that is the same frame they honored a warranty claim for a previous mattress with. The bed is a Rooms2Go wooden frame, with multiple slats and more than 6 posts. I just looked at the tag and couldn't help but notice. It says in capital letters, "THIS MATTRESS IS INTENDED TO BE USED WITHOUT A FOUNDATION." Well... would have been nice to know when the Mattress Firm sales associate told me I needed a box spring to go with it and charged me for it. Honestly, If I had known they were replacing my Caspian foam mattress with a Serta anything, I never would have taken it to begin with. Serta's have always been disappointing and this just proved it again. If you want a mattress to last or if you have back problems, AVOID SERTAS. They don't back up their product and, frankly, neither would I. It's a crap trap. (I do, however, recommend Sealy and its Posturpedic line. They last forever and never sag). And, don't believe everything the sales person says at Mattress Firm. They obviously don't care to know their products and which ones are supposed to have box springs underneath them- they just want the money, honey!