I was able to get my Spigen NeoHybrid frame replaced
Sorry to hear that others have had trouble with their NeoHybrid cases. Like others, my NeoHybrid (purchased in May-June 2013) cracked around the USB port. But it my case Spigen was very responsive and issued a replacement within a day or so.
First, I contacted their customer service to report the problem. I can't remember if the first contact was thru their website, or via Amazon Marketplace, but the rest of the conversation routed through Amazon Marketplace.
(Maybe this is why it was easier for me than for other people since they could see I bought a legitimate non-knockoff NeoHybrid and could prove where I bought it?)
They asked me for a photo of the problem area, which I sent. They immediately sent me a new NeoHybrid hard plastic frame (they didn't send me the black neoprene skin, just the hard frame).
It's been really great ever since. Just comparing the photo of the original frame to the replacement, it looks like they very subtly thickened the plastic opening around the USB port in the most recent set of frames they manufactured. Zero problems since then.
I would recommend that anyone who bought through Amazon contact Spigen via email and see if you can get a replacement frame.