I read a previous guide on this subject and its very pertinent - I got caught too in an almost identical situation. I found Trading Standards were very helpful, but ebay is pretty toothless so dont rely on their dispute console.
I would like to add some other clues to spot a fake: anything sold as or with "summit series" is most likely a fake (I couldnt find this make in existence anywhere on the web let alone on the TNF website). I have also read this on some of the outdoor web forums. The seams will also not be taped (look through the mesh), although the actual jacket might well be Goretex, or Goretex XCR since this isnt the expensive part of making the jacket. If the seams are not taped, you might as well be wearing a string vest..... The size will also be way smaller than you would think, and if the stitching is messy and has loose bits hanging off then its no way genuine. Mine was XXL more like M fitting.
I have read that Berghaus and other makes Lowe Alpine, Sprayaway etc are largely uncopied. If in doubt you can mail the link to the manufacturer (I did this with a Berghaus jacket) who will usually be able to verify its authenticity.