Its like sleeping in a coffin

This mattress leaves impressions of our bodies...It feels like sleeping in a coffin! I have to pull myself out of the "hole" each morning and my back aches tremendously from it! It was okay for about a year before the impressions began to show. There is a hump in the middle of the bed between where my wife and I sleep. We have turned the mattress multiple times as well. My wife is 130lbs and it does the same thing to her side. This is the second Beautyrest mattress we have had in 7 years. We had to have the first one replaced (as it was still under warranty) for the same issue. We are going to just buy an inexpensive innerspring mattress. Would probably hold up better!