The only necklacings that I am aware off, were committed amongst Bantu's themselves. (frightening numbers to be honest) Lynching wasn't done in my time - or not that I would know off. - aside from hangings (death penalty) due to court verdicts. e.g. maybe 10 or so in SWA.
The units I was with. didn't kill civilians "intentionally" - mostly due to crossfires with PLAN or other Angolan associated forces.
And it was damn hard "mostly impossible" - to convince those civilian Bantu's to get away from combat zones. (due to them knowing that once they leave their huts - PLAN and Angolan other's, would rob them blind).
On-top of that our equipment and military-assets were far too "restricted" to allow for mass ground or air-strikes. Even though the US government - especially under Reagan, got us into this "extended mess" - we never received any aid whatsoever from the USA. Savimbi's UNITA was mostly paid for by the USA - IIRC around US$ 80 million in total in the 70'ies and about US$ 150 million in the 80'ies.
In today's value around 3 US$ billion. Uncle Sam just got too much $$