I may have finally convinced someone that they really and truly have sent the wrong part twice. Hopefully when I get back home there will be an appropriate fan available to swap in. As near as I can tell the chain of communications went:

me->guy on phone who knew what I was talking about
phone guy->California team that didn't but maybe now does
California->RMA dept. which made the mistake twice

Can you just give the guy who answered the phone a box of mailers and some parts? That'd work better