A black teenager was apparently asked to leave a swimming pool by the white owner of a holiday resort in Modimolle "out of respect for other people".
The 15-year-old teenager, whose name has been withheld at the request of his foster parents, cried when he was asked to leave the pool in front of other children and holidaymakers, they said.
Tersia van Rheede said she felt helpless when witnessing how heartbroken her child was.
"What happened was unacceptable," she said.
The teen has been living with Van Rheede and her husband, Arie, for the past three years after his mother, who was their domestic worker, fell ill.
"We've known him for seven years already. He is our son and my biological son's brother," said Arie van Rheede.
The family visited the camping resort at the Klipspringer guesthouse and caravan park on December 31.
'They should have explained their situation to me'
Tersia van Rheede left her son and the teen while she went to pick up her husband in the nearby town. The boys then went swimming in the resort's pool.
This is when the owner of the park, Johan Gresse, reportedly told the black teen to get out of the pool.
Gresse told Die Pos, a local newspaper, that he had received complaints from other campers about the black boy swimming in the pool.
The Van Rheedes heard about the incident on their return to the campsite.
"That is when we decided to leave," said Arie.
According to Gresse, the incident had been "taken out of context".
"I feel as though the Van Rheedes should have explained their situation to me before making a reservation. Should I have turned all the other campers away? I think it is just a sign of respect to allow someone else their own point of view. This is an unnecessary incident and now my reputation is being affected."
'This man's racist manner hurt my son'
Gresse told Die Pos he had since apologised to the teen.
But Arie said: "He did not apologise to my son. He must also not now put the blame on other people."
He said he was upset by the incident, as was his son.
"This man's (Gresse) racist manner hurt my son, it dehumanised and traumatised him."
He said he was considering taking action against Gresse.
Approached for comment, Gresse and his wife Elsabe did not want to comment on the matter.
Elsabe Gresse posted on Facebook, however: "Arie go on then, may the Lord bless you."
A post on the resort's Facebook page reads: "If anyone has anything to say about the incident of December 31, you are very welcome to do that by showing your face here on the post. Don't send us anonymous messages, because then I'll call you a coward."
A photo has also been uploaded to the Facebook page with a notice saying "right of admission was reserved".