What has happened to Sealy Posturepedic

I have a huge problem with the quality of my Sealy Posturepedic Queen sized Cypress, firm mattress (Aloe Vera). The mattress was manufactured on the 15th of May 2010 making it 5 Years old. The springs are so soft they no longer, support my or my wife's body weight. The indentations must be close to 80mm deep?? Having always slept on my stomach, I have had to start sleeping on my back or sides as the lack of support kills my back. What has happened? My previous Sealy Posturepedic is now 19 years old and still in use by my son. The new mattress has reached end of life after 5 years. What recourse is there if any? What a let down. So much for a 10 year gaurentee???