Poor durability

We purchased this new mattress/box spring set as our old King foam set from Sears was 30 years old. The Sears set was perfect and the only reason we purchased the new set was because the old set was well, 30 years old. This new Oracle set is now 1 year old and has severe sagging on both sides, such that we feel we are sleeping in "valleys". When rolling over it feels like you are trying to climb a hill. In fact, my wife has given up on it and sleeps in the other room now. Hope this helps in your decision.