Didn’t get the full story

When the mattress was delivered, there was a card attached to it stating “warranty”. I filed it away for possible future use. Two years later, I took it out to see how to resolve the sagging problem. That was the first I heard that we were not to sit on the edge of the bed. Also that it needed to be rotated every two weeks for the first year! I wish they would have put that info in their promotional web posts. So now we have broken down the edge by sitting on it to get dressed. And the mattress sags from body impressions. There is a twenty year warranty, but I don’t want a replacement. I want a mattress that we can sit on and doesn’t need so much handling.