No, none of us have ever used an Alienware case before. You still have never posted pics of the problem area, and as I've stated before, we don't know everything!
I was happy with my Aurora that I got off ebay, despite the protests of fellow forums users. As for the PSU bracket, it did come with one but I believe even without it any standard PSU should fit in there with no problem.
Mine is ORIGINAL from alienware, not dell. So maybe thats what caused the problem.
Its a 5 years old desktop, how do I know? the inside has a blue stamp with that year.
I stopped complaining about it, its was just the PSU supply and how they told me it did not needed special things. (Thats true for the Dell alienwares, So I bet you got a dell not a real alienware.) It just happened that I got a real one lol.