Ernie, it took me a couple of reads, but I think I got it.
It seems like you asked the US or NA distributor to perform a service on a cdp that the original owner bought from a European dealer. The distributor is within his rights, even if it is a paid service. I don't know of a distributor who would touch a product that wasnt imported by him or a predecessor. This is one of the risks of buying second hand imported goods.
Of course, he was a jerk to not make sure he would take care of it before you left it with him. (But, maybe he was in the middle of Christmas dinner - or a football game?) And after he discovered the problem, he might have called you. Did he know that you weren't the original buyer? Hifi component distributors are often really nice guys, but some of them are real jerks.
If you want the mod, it seems to me you should ask a local dealer to sell it to you and refer you to a service center that will perform the work. If you have to buy the parts and do it yourself (if that's even possible), again, I would buy from a local dealer. I don't think the issue of the manufacturer providing service comes up, because all they can do is refer you to their contractual partner in the US or one of his dealers. If the distributor has told the dealers they cant sell the mods to you either, then you just can't have it, and you have to make a decision about keeping the unit.
Otoh, you havent spent the money on the mod yet. Mods are generally just a way to get more money out of you unless there was something wrong in the first place.