sagging latex in 7 years

I expected to have this mattress for 15 years at least since the warranty for 100 percent natural latex mattress was 20 years if we rotated it every 4 weeks. It was so heavy we needed help to rotate it but were faithful to to the routine give or take a week here and there. Now only 7 years later I'm thinking I need a new mattress. Rotating it doesn't seem to make a difference anymore. It sags on both sides. The center of the mattress is a bit of a hill. Now I learn the factory is closed and don't know if I'll be able to request some compensation.