Memory foam is garbage.
I need a firm bed which is what I originally got when I bought this $2300 (retail, but they dropped the price to $1000) 10" name brand memory foam mattress from the local mattress chain. We're talking broken-femur-if-you-jump-on-the-bed firm.
After 4 months it started getting soft.
After 6 months it was COMPLETE MUSH, top to bottom left to right. Instead of supporting, it "conformed" to my body, sinking further where I was heavier, wrecking my back.
Dragged myself back to the mattress store to complain. They suckered me into buying a "firm" coil spring mattress to the tune of another $500, marked down from $750. In my defense I was desperate and in severe pain. Felt okay for a few days, then my back started hurting again, a little more each morning. I knew what was coming.
They won't take the coil spring mattress back. No refunds, even though the salesman said they'd make an exception because that was the firmest mattress they had, and if that didn't work they had nothing else I could use.
Now I'm out over $1500 and I have no place to sleep. I've been sleeping on the overturned memory foam mattress because it was still hard on the bottom, but that's quickly turning to mush as well.
There's nothing left but memory foam out there. Nobody sells inner spring mattresses, let alone extra-firm, anymore because it's not "in." Memory foam is GARBAGE. It will get soft and mushy after 6 months. It will fail on you. It will leave you waking up in blinding pain at 4 in the morning.