Last year I was awarded South Africa’s highest honour – the Order of the Companions of OR Tambo. It was one of the proudest moments of my life. So why was it bitter sweet?

The award was given for “an excellent contribution to the fight against the injustices of apartheid, and unwavering support for the South African liberation movement”. But the sad truth is that Nelson Mandela’s rainbow nation has, in just 22 years, gone from hero to zero. The country’s media castigate President Jacob Zuma for “looting the country”, international investors are jumping ship, and criticism is everywhere.

Much of the condemnation comes from jaundiced whites – those who reluctantly praised the “Mandela miracle” but never accepted the consequences: the demise of their grotesquely privileged existence.

I can – and do – dismiss such voices. But I cannot ignore those who sacrificed so much for the freedom struggle, and who are now dismayed at the squandering of Mandela’s legacy.

Veteran activists such as Ahmed Kathrada, one of Mandela’s closest comrades on Robben Island. Or Barbara Hogan, a former ANC government minister who was tortured in an apartheid prison. Recently she broke ranks, declaring: “Zuma must go. This man is creating economic sabotage.” Her remarks were echoed by ANC struggle stalwart Denis Goldberg’s call for a “top to bottom leadership clearout” and an end to corruption.

Zuma has indeed allowed corruption to flourish until it poses a cancerous threat. Cronyism has replaced merit, not only in the public services, but in the parastatals. The country faces daily “load shedding” (electricity cuts); South African Airways is almost bankrupt, with its excellent safety record compromised; and the water system, once the cleanest in the world, is in disrepair. And yesterday, after a scandal lasting two years, Zuma agreed to pay back some of the public funds he’d used to upgrade his private mansion.

The image of white students in Cape Town forming a human shield to protect black classmates from the batons of riot police would surely have made Mandela smile.’ Photograph: Mike Hutchings/Retuers

Despite spending more on education than any other developing nation and doubling school attendance, South Africa is ranked 138 out of 140 countries by the World Economic Forum, below desperately poor Burundi and Mauritania.

South African schools are not short of textbooks through lack of funds, but because budgets are badly managed or siphoned off. Yet I have met inspirational teachers whose pupils achieve extraordinary exam results, often studying by candle light on an empty stomach. One such student now works as a gardener at the school where he excelled. He counts himself lucky: unemployment among black youth is shockingly high – as much as 65%. Mandela must be turning in his grave.

But a vibrant civil society, forged during the anti-apartheid struggle, continues to challenge government attempts to undermine democratic structures and processes. It is buttressed by a vigorously independent media and a noisy political opposition.

Together they have fought draconian legislation like the protection of state information bill, which prevents journalists from exposing corruption and state abuse. They have battled to safeguard institutions like the South African Broadcasting Corporation and directorate of public prosecutions, where top positions have fallen into the laps of political cronies.

When the ANC gained power in the country’s first free elections in 1994, a deal was struck to ensure a peaceful, economically stable transition. A black majority ran government but the white minority still ran the economy – albeit with a co-opted black, overwhelmingly ANC-aligned elite.

Now, people like ANC liberation hero Ronnie Kasrils see this as “the devil’s pact”: a terrible betrayal of the poorest of the poor. Trade union leader Zwelinzima Vavi warned in 2010: “We’re headed for a predator state, where a powerful, corrupt and demagogic elite of political hyenas is increasingly using the state to get rich.”

In 2012 the Marikana massacre of 34 striking miners, at least 14 of whom were hunted down and shot from behind by predominantly black police, further symbolised the unresolved legacy of apartheid: a wealthy white-owned corporation pitted against poor, black migrant workers.

Last year, very different protests on university campuses forced Zuma to reverse planned fee increases. The image of white students in Cape Town forming a human shield to protect black classmates from the batons of riot police would surely have made Mandela smile. But he would also have understood the terrible truth: two decades after the death of apartheid, white privilege is still alive and well.

Perhaps we expected too much. Perhaps it was naive to think that the ANC – for all its moral integrity and constitutionalist traditions – could be immune to human frailty, especially in the face of such immense social inequalities. Was it ever possible to launch meaningful economic reform in today’s climate of neoliberal globalisation? As I know only too well, it was hard enough for Labour in Britain.

Next week Zuma will give his annual state of the nation address. But unless the ANC can forge a new social compact, South Africa could again become as ungovernable as it was during its bleakest years. Perhaps the “Born Frees” – those young South Africans who never knew apartheid, and who already comprise over 40% of the population – will reclaim Mandela’s legacy for the 21st century.

For this beautiful country remains an inspiration: marvellous to visit, and joyously transformed in spite of the many challenges that remain.