Simmons Comforpedic — Sagging

Mattress sagged after a month (last August). I called steinhafels mattress immediately and they sent someone out. It was indeed sagging, but not enough to warranty the mattress out. This replaced a previous steinhafels mattress that was also warrantied out after a year. I went back to credit card company, but they could not help since 4 months had past. It is now sagging 3-4". We are not excessively heavy at all and try not to sleep in the same spot. When you sit on the edge of the mattress or the side, it completely sinks. My back is not aligned and low back droops when trying to sleep. When I roll over, I have to take a deep breath. I frequently wake up with my hand, shoulder or neck asleep and horrible stiffness/back pain. This mattress was $1500 retail. I only got it because I got a $500 store credit from the last mattress. I will never return to steinhafels for mattresses nor buy a simmons. It is true what they say, they don't make mattresses like they used to. I will be disposing of this mattress and getting a cheap, spring mattress since it will probably yield a better night's sleep!