I think the many users of the Duet who have had complete success, are very happy with their purchase, and who enjoy the assistance given on this forum would disagree with you.
It seems clear from your posts that English is not your first language, so you may have misunderstood some of the Wiki instructions. For the same reason you may also not realize how rude your posts appear to an English speaker. David, Tony, and the other frequent posters here are the most helpful I’ve found on just about any forum. If you would work with them rather than arguing I’m sure you would get things worked out.