Back in April 2012, when 5D3's were as rare as Unicorns for those like me who had not prepaid and preordered them, I was calling to and searching on the net for anyplace which had a 5D3 that they would sell to me. Nothing came up for more than a week. Then, in a complete surprise, while on line at another photo related site, I spied an easy to overlook, tiny, postage stamp sized display ad from Dell saying they were offering 5D3's for sale. Not really believing it, I called them anyway, as I had bought computer gear from them before and I had very little to lose. To my utter amazement, they had just gotten about 30 or 40 in stock and were indeed able to sell me one - at the $3,500.00 full price, of course, while many others were selling it at $300.00-$500.00 over retail to non-preorder customers at the time. I got the perfectly new, perfectly clean USA model just when they said I'd get it, and it has served me very well since.
Just sayin' that you don't need to ordinarily fear ordering from Dell.com. They're a big company with a reputation to protect, and they would never, ever purposely "stiff" a customer with a scam like the OP described. Say what you want about their customer service or their computer gear quality, but the OP's story goes beyond any mistakes in those areas by miles; this is criminal fraud, not bad customer service management. As to them needing to investigate it, well, think about it. I'm not questioning the OP's honesty, but put yourself in Dell's position for a minute. I could ridiculously easily get a camera shipped to me, remove the camera and the other content from the Canon box, put woood in the box, and then photograph the "unboxing" as though the wood were what I actually received in the first place. Dell was nice enough to offer $100.00 for the unfortunate OP's trouble, without any corroborating evidence, but they will have to investigate, and perhaps have criminal charges filed against whatever middleman might have been the guilty party here, before they can try to ship a camera to the OP again.
Insanity is the definition of continuing to do the same thing over and over, but expect the results from your identical actions to be different, just because you are repeatly doing it. The people at Dell are not insane.