Good for the 1st night only

I purchased the Vera wang serta with the think pillow top in August of 2007. It sat unused for a year and the 1st night my ex and I slept in it I thought it was amazing. Then we got up. There was a whole body indentation in the bed where he slept. He's not a big guy. Within 2 months of me sleeping in it I had to alternate which side I slept on as it was already sagging. Since then I've maybe slept in the bed 3 night a week, opting instead to sleep in the guest room on an inexpensive and more comfortable mattress. After 2 years I tried calling the store I bought it at but they were out of business. The sagging is beyond painful. I have to get up multiple times a night to stretch out the kinks in my back. I will never purchase a serta ever again. I would love for someone to inspect it but I've never been able to get assistance. I understand products fail, but customer service shouldn't.