i wouldn't use them because when ever i've looked at their website it always looks crap!!!
i wasn't having a go at you by saying you were having to have the arch work done so i hope you didn't take it that way.
all i was trying to do was state that the adaptors they sell do make porsche wheels fit golfs, so i don't think you can do them on false advertising, other people with different set ups can get away with it, just unfortunately for you the set up you have doesn't allow this. which is why you had to buy the wider adaptors.
i'm not up on the law as you seemed to have checked this out, but i always thought it was at the companys discretion for their return period so sorry if i got that part wrong. in which case i'd pursue it further if you feel you have a case.