Varenda Gouws, 45, said Krugel led her and husband Willem on a wild goose chase after son Rayno, 20, went missing last year during a hiking holiday.
She gave Krugel a hair from Rayno's razor. He fed it into his Matter Orientation System, that he claims combines DNA testing and GPS - satellite technology to track down missing people anywhere in the world.
She said: "I can't say this machine doesn't work - but I know for a fact it didn't work for us."
Rayno had last been seen taking a bus to Knysna in South Africa's Western Cape region.
Varenda said: "First Krugel told us Rayno was still in Knysna so we went to Knysna. Then he said he was in Port Elizabeth 150 miles away so we went to Port Elizabeth. Then he was in East London so we went there. Then he told us 'No, he's in the Transkei.'
"It was an endless track. We drove through South Africa for 4,300 miles. He absolutely convinced us saying 'Rayno is moving'. He said he must be in a truck or a car because he was moving so fast.
"Every time we left our jobs and packed up and went to these places and put articles in the newspapers. It cost us a fortune.
"But it's not the money, it's the mental torture. Being told your child is all right, he's moving around. We thought, 'Why doesn't he contact us?'"
Rayno's remains were eventually found eight months after he vanished in a forest outside Knysna. It is thought he died from a snake bite.
Varenda said: "It was clear that he had been dead for eight months because there was no flesh on the bones and there were ferns growing through the body.
"But when I phoned Danie to tell him, he was really aggressive. He said it was not possible. He blamed me.
"He said 'This is a lie. Nobody can tell you how long a body is dead'.
"He didn't want to hear he had made a mistake."
Varenda said that after her experience she would never recommend Krugel to anyone. She added: "He told us he could definitely find Rayno and we believed him. We trusted him. He told us he can find anybody, anywhere in the world.
"I feel betrayed. Eight months is one hell of a time to look for a child - to be told he is alive.