On Monday, commission chairperson, Deputy Chief Justice Raymond Zondo set a date for the former president to appear again before the commission. 

Zondo said that appearing before him is non-negotiable.

The foundation says it is dismayed by what they call an extraordinary media conference designed to humiliate Zuma and his attorneys.

They describe Zondo's comments as an unjustified and prejudicial attack on Zuma.

The JZ Foundation wants to know why a similar press conference was not called to address Public Enterprises Minister Pravin Gordhan, when he failed to file an affidavit to explain his non-appearance.

The letter goes on to say Zondo is obsessed with Zuma.

eNCA