Thats strange, a 32A 3ph plug should fit in a 40A or 50A socket, the 32, 40 and 50 all have the same pin size, there is just a key way that prevents a higher amperage plug going into a lower amperage socket. Obviously, all sockets must have the 5th neutral pin for the UMc to work, so 4 pin sockets are no good.
See this Clipsal catalogue, page 15.
http://updates.clipsal.com/ClipsalOnline/Files/Brochures/I0000112.pdf
Tesla should be selling the pigtail with the 20A Aussie plug rather than the Euro plug, and offering a 32A adaptor.
Are they selling any 15A or higher 1 ph pigtails yet?
Adam.