We bought a King Coil pillowtop about 7 years ago to replace a 15-20 year old foam mattress that was still fairly comfortable but showing its age a bit.  What sold us was the firm support softened by the pillowtop and the extra support padding on the sides of the mattress, and figured a 10 year warranty was as good as we would get.  After 3 years or so we started having the sagging where we normally sleep, and it just kept getting worse and worse, as well as the side of the bed collapsing if you lay too close to the edge.  A few months ago I was making the bed and got scratches on my leg - bits...