After consulting his GP, Dr Andrew Torbet, and following Dr Ratna's recommendation, it was decided that Brad's intake of sodium valporate - a mood stabliser - should be reduced.
Dr Torbet later wrote to the Health and Disability Commissioner that "his mood was good" and Brad was happy with the new regime.
Both doctors did not consider Brad required psychotherapy and Dr Torbet said he had denied having any suicidal thoughts.
But in July, Marianne Milne phoned the Bethlehem Medical Centre worried about her son's mental state. The next day, Brad consulted Dr Torbet and asked for a change to his medication.
Dr Torbet did not consider that appropriate, as the regime had previously worked well, but days later consulted Dr Ratna, who agreed to a change to venlafaxine - an anti-depressant - and recommended counselling would be appropriate.
Dr Torbet then contacted Brad and said his medication could be changed, although he would need to withdraw from the medication he was taking, and that he would be unable to prescribe it immediately.
During these last weeks Mr Milne said his son had told his boss he was suicidal. "We could see how bad it was, but the people who should have been able to see couldn't," he told the Herald.
Mr Milne is adamant his son suffered from bipolar disorder - something Brad could not even acknowledge when his mood was good.
After his death, the couple lodged a complaint with the Health and Disability Commissioner.
The decision they received in April - which included one expert's view that there was "insufficient detail" to ascertain whether Brad's diagnosis of bipolar was reasonable - found that the changes made to his medication prior to his death were appropriate.
It left the couple "angry and disillusioned" and with yet more questions, Mr Milne said.
They responded criticising the scope of the commission's investigation, what they saw as a failure to review all of the medical evidence and make recommendations, and a lack of robustness.
They questioned why Brad's medical notes had not followed him from Southland, why he was not asked when he first sought help, why they were not asked about his early requests for help and why his partner had not been consulted.
"But I wasn't surprised, put it that way," Mr Milne said. "That's why we just sat down and wrote a response. And we are prepared to go further with it if we have to."
Meanwhile, the couple, with help from others including Dame Susan Devoy, have organised a function next month to raise awareness around depression and suicide prevention in the hope of sparing other families their pain.
