South Africa coach Mark Boucher admitted his team "got the plans badly wrong" in a thrilling decider as they suffered a Twenty20 series defeat against England.

In the SuperSport Park clash, South Africa piled up 222-6 to lay down a tough challenge to England, yet the tourists powered to victory with five balls and five wickets in hand.

England needed 62 from the final five overs and got them in scintillating style, as Eoin Morgan and Ben Stokes dominated against the home attack.

Andile Phehlukwayo and Lungi Ngidi came in for the most grievous punishment as England secured a 2-1 series success.

Boucher reflected on the ups and downs of South Africa's display.

"A couple of questions answered, yes - maybe in a positive way, maybe one or two in a negative way, but at least the questions are answered," he said.

"And I think we're getting a good idea of what positions we need to fill and which players are putting their hands up for those spots."

Looking at how the match finished, Boucher said in a post-match news conference there was a technique issue with the death bowlers that needed to be addressed.

"We got the plans badly wrong there. We did speak about that, trying to bowl more yorkers," Boucher said.

"It's quite difficult to train those sort of things now because we play and we travel. So the skill I don't think is where it should be and that's something we need to work on."

It remains to be seen whether South Africa's batting line-up will include AB de Villiers by the time the World T20 comes around in October.

Scoring runs was not the most obvious shortcoming for the Proteas on Sunday, yet again the De Villiers topic cropped up.

The veteran retired from international cricket in 2018 but looks likely to return at least in the shortest format later this year.

Boucher said: "We'll know pretty soon what's going to happen with him. I'd like to have our best players there.

"If AB is in good form and raring to go and if he makes himself available ... if he is the best man for the job, then he must go."