I just went through a similar but completely opposite experience. I got the same mattress this guy got and after a week I noticed it started sagging in the middle. I called the store. They asked some questions to determine whether I just needed to get used to it or if there was something wrong with the mattress. They sent somebody out to look at it and then said they'd swap it out for a new one at no charge, even though their receipt said I had to pay $79 for transportation since the manufacturer's warranty doesn't cover that. I was apprehensive about getting the same mattress so I went back into the store where I bought it to try out some others just in case. The salesman told me how a few percent of all mattresses are defective and, from the manufacturer's point of view, it's cheaper to swap them out than to get the defect rate lower than that. So I ended up getting the same mattress, which hasn't had the same problem and I've never slept so well. I love it. When you get a defective mattress, it sucks. But they took care of the problem in the most reasonable manner I can imagine at no cost to me. That's why I had to respond to this guy's gripe.
I find it interesting that this complaint complains about a "$300 service charge." When I look on the back of my receipt, it lists a bunch of exchange fees for different situations, but nothing close to $300. In fact, the more I read, the more I think this guy has his facts all screwed up. Let's start with how it explains that the mattress manufacturer provides the warranty, not the retailer. So if there's a problem with the mattress, take it up with Serta. If the problem doesn't fall under the warranty, I'm surprised the mattress sellers even offer to exchange the mattress. Second, it says right there on the receipt the charges for exchanges. If you don't like it, don't sign it. I shopped at 3 other places before buying and found the people at Rockaway to be by far the most knowledgeable and least pushy. Plus Sleepy's wanted to charge $79 for delivery and another $30 to take away my old bed. At Rockaway, it was free. It sounds to me like this guy just didn't choose the right mattress and wanted a different one for no charge. In that case, the 800 number people were right. "You picked it so its your fault"