Sandile Thabethe, 25, pleaded guilty to being part of a gang that hit and kicked Enoch Mntungwa "all over his body".
He was sentenced to 18 years in prison.
The intensity of the assault increased when he would not tell Thabethe's gang the pin numbers of the bank cards of which they robbed him.
Thabethe said he, Mntungwa's girlfriend, and other men plotted to rob him after they were told that he had a lot of money.
In the end they did not succeed in stealing much from him.
Judge Leona Theron said although Thabethe had pleaded guilty to the assault and agreed to help in the prosecution of the other gang members, the aggravating factors far outweighed the mitigating factors.
She said the prescribed minimum of 15 years was not sufficient for this incident.