To reitterate what the factory said Richard, you are the only person to complain and you have had your payment refunded and the issue of the corners has been addressed, at my expense.
You talk about receiving "no information whatsoever on the design, the materials, or the performance", I've already explained that I had no more information about these matters than anyone else prior to the product arriving, yet it appears as to me as if you expect the factory in China to have produced a detailed product specification sheet for it and to have provided that to me prior to placing the order. Have you ever seen ever the kind of data you're talking about displayed for any Chinese light diffusers, or even for that matter the Lastolite Hilite itself? No, neither have I.
Most people realise that if one is only prepared to pay the price of a Chinese copy then one has to accept a trade off, whether it be in build quality, performance or a mixture of both. You have complained about every single facet of this product, so we get the idea, you don't like it.
That's fair enough, I'm doing my best to address the issues that you, and only you have raised, however as you no longer own one of said products I can't really see how it effects you in any way, shape, or form any more or indeed how you can contribute anything new to this thread.