They should at least be able to get the parts you're looking for. But that's absolutely ridiculous that they won't work on OEM equipment purchased by someone else. Fuckin dealers
Insurance companies do this all the time. Just this part Oct my warranty company bought and shipped an OEM steering rack to my dealer for install. The dealer priced the part at an outrageous $900, and the warranty company said they could get it for half that. I made sure the dealer confirmed it was a legit new OEM part and it was.
Your best bet for install might be to find a local forum member and buy them some beer and pizza or something. Or go to a competent shop.