The Australians, who won the opening match 66-33 and the second fixture 45-38, clinched a 3-0 series victory.
The hosts, in search of a consolation win, led from the start but the tourists stayed in touch and drew clear in the dying stages of the third quarter.
Maintaining their intensity, the SA squad fought back to trail 37-36 in the final period, but their opponents displayed their class to clinch the win.
“It was a great experience to get this exposure at international level. I think we gelled nicely and did well on court,” said Zandre Kruger, captain of the SA U-23 invitation team.
“In every position we had them but they just showed more composure. If we play more often at this level we can win games like this.”