First, I don't sell Serta BUT here are some guidelines that are pretty universal. 1) Did you purchase the matching box springs or just the mattress? If you reused a old box springs that is Serta's way out so to speak. Simply put the wear on an old box springs will transfer quickly to the mattress. 2) How much sag is in the mattress? Run something straight (string stretched tight, long board, etc) from head to foot over the sagging area to see how much gap or sag is there. Most manufactures don't consider it a warranty issue until the gap is 2" or more. The plusher the mattress the more it will compress. This "compression" MAY be what you're seeing. 3) Is the "sag" just a cosmetic problem or is it something you can feel. A certain amount of compression is normal but too much is a warranty issue. Contact the store where you purchased it or Serta and ask about the length of full warranty. At less than a year old I very much hope you're still under full warranty. A good quality mattress should have a FULL (not prorated) 10 year warranty. I didn't really answer your question but I hope this background information will help you (if not today then maybe in the future). Sweet dreams!

Hi Mike, I hate to be the one to break it to you, but $500 is a low end price.... The procedure from here is pretty much set in stone. Call your retailer and have them initiate a warranty claim with the manufacturer. Once it has been inspected and authorization is given to exchange it, I'd suggest going with one of the other brands that store carries. If you must deal with the factory directly, should your retailer be out of business, or just one that doesn't do customer service, you'll be stuck getting another Serta. Check you mattress over for stains. If you find any, this all becomes moot. A stain on a mattress automatically voids the warranty. If you get to the point where you are faced with making a new choice, write me with what you have available to you and we'll go over your best options.

Should be a 5 year full replacement as long as the mattress is not stained. Your retailer will have a warranty process to go through in order to determine what the issue is. Contact them first and see if they can offer a replacement. If it is stained, then they will likely refuse warranty approval. The 5 year full warranty covers sagging 1.5" or more. You can measure the sag by putting something flat across the top of the mattress over the sagging part, then measure down. String or a yard stick works just fine.