Tommy Reffell scored his first try for Wales but it was South African duo Jasper Wiese and Handrè Pollard who celebrated a series victory in Cape Town on Saturday.
Leicester Tigers back-rower Reffell, playing in his third senior international after a debut in the opening Test of the summer, put his team’s first points on the board midway through the first half after the Springboks had led 10-0 with all the points coming from fly-half Pollard.
Wales had recorded a first-ever win in South Africa a week earlier to set up the decider and trailed just 17-14 early in the second half before the Springboks pulled away to win 30-14 and ensure series victory.
Tigers hooker Juilián Montoya shared in series victory for Argentina against Scotland, though he missed the 34-31 victory in the third Test which was sealed with a late try. Matías Moroni started at centre in the final action of the summer series.