Paramedics pronounced the woman - who has not been identified - dead at the scene of a auto crash that killed two others on June 24, with the ambulance company claiming she showed "no form of life", Times Live reported.
Later, when a morgue worker checked on the body in the fridge, they found that the unnamed woman was still breathing.
The woman's not the first person to be declared dead in South Africa but later found alive in a morgue.
The woman was transferred to a Johannesburg-area hospital.
"When our ambulance arrived on the scene, we followed all the procedures", Gerrit Bradnick, operations manager at ambulance service Distress Alert, told the German DPA news agency.
"All the right checks were done - breathing, pulse - so the patient was declared deceased", Mr Bradnick said.
"Paramedics are trained to determine death, not us", a source at the Carletonville mortuary told the Sowetan newspaper.
He said: "When he pulled out the woman's body' he saw that she was breathing".
The woman, who was taken to Carletonville hospital after being found alive in the mortuary, had shown no signs of life when she was attended to by first responders, added Bradnick. "Can you imagine if we had begun the autopsy and killed her?"
"As a family we won't talk about this unless the police, paramedics and the mortuary officials who were involved are present".
The man said that the family of the woman were in shock.
The victim has not been named, but the BBC reports that her family is demanding answers because, thus far, they say authorities have offered them no "clarity" regarding how the massive mistake was made. "There is no proof of any negligence by our crew", he said.