She said of the 1.5 million face to-face interviews conducted last year, there had only been 147 complaints lodged with the department.
Ms Bradford claimed earlier today that the young mother, Tara Marks, approached the Rotorua Work and Income office for a food grant last month.
"As she stood with her baby in her arms asking for assistance the case manager laughed at her and told her to f*** off," Ms Bradford said.
The incident was originally reported by the Daily Post. The paper reported that the case manager is under investigation and has agreed to take leave.
It also reported that Ms Marks may have called the man a "derogatory homosexual name" but Ms Marks denied the claim. She said she was denied a food grant before being sworn at.
"I couldn't believe it. Nobody deserves to be spoken to like that ... He shouldn't have done that in front of my son. I don't think he should be dealing with the public," Ms Marks told the Daily Post.
She has made a formal complaint and received a call last Monday from a staff member investigating the complaint.
The Daily Post reported that senior staff planned to meet Ms Marks to apologise for any distress the incident may have caused and to get her side of the story.
Ms Bradford said the Rotorua case was not isolated.
She said another woman who visited the Gisborne office was subjected to "an unscheduled bullying session" with "three staff members harassing her at once".
Ms Bradford said the woman is now too frightened to return although her subsistence income depends on it.
In another incident, a case manager is reported to have screamed in the face of a person approaching them for assistance.
Ms Bradford said the Government had to step in and include beneficiary advocacy groups in the training of frontline staff and apologise to people who have been abused.
WINZ has not yet responded to questions about the alleged incidents put to it by nzherald.co.nz.