The Administrative Appeals Tribunal has heard evidence of a manager miming shooting an employee at a meeting at the welfare agency's business integrity unit at Hurstville in Sydney's south.

Another worker, left a nervous wreck and begging not to be sent back to "that horrible place", was forced out of her job for 11 months suffering a psychiatric condition.

The woman, Amanda Kosteski, won her case before the tribunal this week after her claim for workers' compensation was initially refused.

The department insisted she was treated "reasonably" in the case's wake. It refused to comment on problems at Hurstville, saying it would not publicly discuss workplace culture or performance issues at its individual sites.

Do you know more? Send your confidential tips to ps@canberratimes.com.au

But after hearing evidence about the conduct of the department's managers at Hurstville between 2010 and 2012, the tribunal granted Ms Kosteski's claim and was scathing of the department's response to the issues raised in her case.

The tribunal heard the department's national management was aware of problems at Hurstville after several allegations of bullying were raised anonymously.

In 2011, an independent officer was appointed to investigate the culture of the unit and the behaviour of its staff, but it is unclear what happened to this inquiry.

Despite expectations the investigating officer would finish a report in early 2012, a Hurstville manager told the tribunal she had not seen the document or even a draft, and her own boss claimed to have no knowledge of the fate of the investigation.

The department's media unit refused to answer questions from Fairfax Media about the investigation.

After a series of run-ins with her bosses at Hurstville, including witnessing the alleged shooting mime and hostile "interrogations", Ms Kosteski was transferred temporarily to another Centrelink site in Sydney.

But when her secondment ended - and she was told she would have to return to Hurstville, the 17-year Centrelink veteran was so terrified of her old bosses she broke down, lost 20 kilograms from fear and anxiety and was unable to go back to her job.

Three doctors, including one appointed by DHS, found she was suffering from a work-induced psychiatric condition, although their diagnoses differed slightly.

Ms Kosteski returned to work last October at a different office, and in his judgment tribunal member Robin Handley ordered that she be paid compensation, finding that Centrelink's efforts to help its worker were too little too late.

"Nobody appears to have taken responsibility at the appropriate time for assisting an employee who was showing clear signs of distress," he wrote.

"Action was taken by Centrelink to address the problem subsequently but by that stage the damage had been done.

"I note the expert witnesses commented on the poor workplace handling of her situation."

A departmental spokeswoman defended the department's record on workplace behaviour.

"Bullying and harassment are unacceptable and the department has strong code of conduct measures to address instances of inappropriate workplace behaviours," she said.

"We have a strong track record in providing our staff with clear processes to address difficulties in the workplace."