West Indies tour of South Africa hit a new low when they were bundled out for 122 in under 34 overs to lose the third ODI by nine wickets at Buffalo Park.
The Proteas chased down their modest target with 25.2 overs to spare for the loss of only left-handed opener Rilee Rossouw as Hashim Amla finished unbeaten with 61 and Faf du Plessis not out 51.
South Africa hold an unassailable 3-0 lead ahead of matches in Port Elizabeth on Sunday and Pretoria next Wednesday.
Imran Tahir had the best bowling figures for the home side of four for 28, but the pick of their attack was seamer Vernon Philander, who removed the dangerous Chris Gayle (one) on his way to three for 27 in eight overs.
After 730 runs were scored in the second ODI in Johannesburg on Sunday, only 245 were needed in East London as West Indies capitulated on a wicket that was more of an even challenge between bat and ball, but nowhere near as hazardous as the tourists' low total suggests.
Marlon Samuels top-scored for the tourists with 26.
West Indies 122 all out in 33.4 overs (Samuels 26, Tahir 4-28)
South Africa 124-1 in 24.4 overs (Amla 61*, Holder 1-14)