I purchased Sleep Number bed 4 years ago and have been sleeping in a hole for the past two years. The king size mattress sags in the middle where the two air mattresses come together. There is a foam pad that is 2" thick that is between the mattresses. I called customer service and they wanted to send me a "riser" for the middle of the bed. Are you kidding me!! After two years, a mattress should not sag in the middle. I wake up struggling to get to the "high" side of the bed, with my back hurting. Their... read full review »