Hi Pete,
FWIW, I've had excellent results ordering replacement parts from Tamiya USA via the "support" page on their website. I've ordered parts 3x from them, and they have yet to charge me for parts (or shipping) even though I offered to buy the replacements. And 1x they sent me an entire engine sprue rather than just the needed parts. That's great customer service.
I would assume that ordering parts in Europe is probably on a country-by-country basis via their local/regional agents, but check out the Tamiya Europe website and see where that leads: they might have a general support page or otherwise tell you how to contact the agent for Austria, who ought to have its own customer support service.
Best,
Chris