I am not sure where to post this so I will try here, I bought a cheap 3 seater settee for the backroom about six months ago for £450, it has 2 cushions filled with memory foam, the size of each cushion is 700 x 700 x 150 but after sitting on it for about 1/2 hour there is a deep hollow in the cushion which takes 10-15 minutes to come back to normal, so I thought it was cheap memory foam, and I would like to replace it with good foam, does anyone have any experience with this, and what sort of foam to get?