Poor memory foam

We purchased an Aireloom mattress July 07, from a store called "The Dump". We are very unsatisfied with this mattress. It has two large indentions on each side, where my wife and I sleep. The memory foam built into this mattress has completely broken down to the point that when you lay on it, it completely compresses at the points where there is the most pressure. My wife and I are not large people either (apprx 170 lbs each.) You have to roll up a hill to turn over, and it's very difficult to stay on the hump that is in the middle of the mattress. After about one year of using this mattress, it was beginning to hurt my back, and now has become unbearable to sleep on. I haven't tried to recieve warranty service, and after reading these reviews, will probably just throw it away and go with a different type mattress (one that does not have memory foam.) I think it would be much better to buy a memory foam topper, than to have the memory foam built in to a mattress, because I really doublt that any memory foam in any brand of mattress will last more than a couple of years. The model that we purchased was 0142DA26071DM also called La Rarena Eurotop. Hope this helps others who are thinking about this mattress, or any mattress that has memory foam. We paid about $2500 for just the mattress and springs.