Toyota does same thing
I had a similar, though much less costly, experience with Toyota. I bought a new Avalon and was told Toyota would reimburse me the cost of having my lift moved from the back of my old car to my new one. I paid to have the work done, dutifully got all the required paperwork completed and mailed it to Toyota. I got a notice back that they would not reimburse me because the car was not rated for the size hitch required for the lift! Rather than get my blood pressure up, I just dropped the whole thing. I hope you will keep fighting. I get really disgusted at how everyone seems to want to take advantage of the handicapped. It seems everything we must buy is incredibly overpriced! Good luck.