I understand the OPs frustration. I had a similar experience with a local shop a few years ago. The owner touted how he was the only shop in the area to have a Philwood spoke cutter to cut custom lengths. I had a spoke break on a wheel and took the wheel in to get it replaced. When I picked up the wheel, they had used a nonbutted spoke despite the others clearly being double butted. When I asked, they said they don't have any double butted. When I got home and went to tape the wheel, I found they had cut the spoke several mm short and it didn't reach the neck of the nipple (these were factory wheels with aluminum nipples). Needless to say, I never went back.
It is frustrating when you go to a shop to purchase a part, pay retail and get the wrong part. Similarly, it is frustrating when you pay for a shop's knowledge and labor, only to get garbage in return. I have learned, if I want to be sure it is done right, do it myself. Unfortunately, as I have multiple friends who have similar problems with poor shop work, I seem to get stuck doing their repairs and ordering parts. As others have said, it is like magic, I put in an order with Jenson or Universal and I always get the right part, as I can check the manufacture number and confirm before ordering. Ironically, I also normally get the part much faster, as I don't have to wait for them to put in their batch order like a shop.