"HiTech RedNeck" wrote...

I have had this mattress for slightly over a year and I have had to
send it back twice for repairs because it 'sags' after a few hours of
sleep and starts causing back pain

Well that's the memory foam developing its memory... working as advertised.

Not really...

Though cheap "memory foam" may sag as described, good, temperature- AND
weight-sensitive "memory foam" supports without sagging. I also have chronic
back problems from surgery over 20 years ago. Waterbeds are the absolute worst,
and so far the Tempurpedic is the best I've felt -- much better than a simple
"stiff" mattress.