According to the Sunday Times, Madonsela sent the letter to Zuma on Thursday. In it she also accuses him of failing to tell parliament when he plans to pay back the money.
Madonsela also claims that Zuma has not yet responded to her report – this despite the president’s office saying he has.
In her report, Madonsela states that Zuma has to repay the cost of items not related to security. This includes a family visitors’ centre, a swimming pool, a cattle kraal and a chicken run.
Madonsela also lashed out at Zuma, accusing him of being guilty of an attack on the constitution and the rule of law by granting Police Minister Nkosinathi Nhleko the power to review her report, reports the Sunday Times.
Three investigations
There were however, three different investigations into the upgrades, done by the joint standing committee on intelligence, the public protector and the Special Investigative Unit (SIU).
Public spending on the security upgrades has turned into one of the major controversies of the Zuma presidency, as costs escalated to R246m – especially when it emerged the project included a pool (dubbed a "firepool" by the government), an amphitheatre, a cattle kraal and a chicken run, among others.
In her report earlier this year, Madonsela found that Zuma and his family had unduly benefited from the upgrades and recommended that he repay some of the money.
Zuma declined to respond to Madonsela's report in full within the required fortnight and said instead he would wait for the SIU's findings.
The presidency and the African National Congress's chief whip Stone Sizani disagreed with Madonsela's statement, saying Zuma had responded.
The National Assembly on Tuesday resolved to set up an ad hoc committee to consider Zuma's response.
But parliament's question time was suspended, and then adjourned on Thursday when the Economic Freedom Fighters disrupted parliament.
This came after Zuma flatly refused to answer questions about the upgrades put to him by EFF leader Julius Malema.