CYF officials in Papakura, she said, requested her to keep the boys past one week.
"They gave me $100 food grant in the first week, another $100 grant in the second week only after I chased them up, then $150 and another $150 food grant on Wednesday.
"I just feel they've dumped them here and washed their hands of them."
She said she was given one day's notice by CYF to take one of the boys to a pre-arranged appointment at a health clinic, and has also had to drive another to see a doctor as he couldn't sleep properly.
"The boys need clothes too. I bought a pair of boots for rugby league training the other day," she said.
Apart from the brothers, she also looks after her 3-year-old grandson and says the extra workload without adequate financial support is putting strain on her family.
Northern regional director for CYF Sharon Thom said her office had been actively supporting the woman while working through longer term care arrangements for the boys.
"We have provided help with costs associated with caring for the boys, including for food and clothing much more than the $100 a week suggested.
"We are also reimbursing her for medical expenses. This placement was intended to be a temporary arrangement."
She said while their placement had gone on for longer than originally intended, it had happened with the consent of the grandmother.