Australia Post has defended its rough run.

Australia Post CEO Christine Holgate was grilled at a parliamentary hearing this week, after half-year profits fell 46 per cent to $83 million and losses from letters rose to $87 million.

Labor senator Nita Green asked about the dire letter results ahead of an upcoming EBA negotiation with workers.

“We [are] trying to understand what is going up and what is going down and where things are being moved to make things seems a bit better or a bit worse,” Senator Green said.

Ms Holgate was asked how a $284 million loss in letters in 2014 returned to a $158 million profit by 2017, before dropping back to a $40 million loss in 2019 and an $87 million loss in the latest half, even though stamp prices increased over that period.

She said internal ‘transformation’ had come at a significant price.

“Our most significant challenge is managing the tipping point of that transformation for our delivery network, which is about 70 per cent of our costs, which is actually now in need really of a significant transformation,” Ms Holgate told the committee.

She was also asked about a series of recent departures including former CFO Janelle Hopkins, chief operating officer Bob Black and head of corporate services Philip Dalidakis.

They left after long term incentives for executives were cut in the wake of controversy over former CEO Ahmed Fahour's pay.

The current CEO gave various explanations, including that Christine Corbett, a former chief customer officer, resigned before she joined, other executives had only be brought in temporarily, and some were looking to spend more time with their families.

The Federal Government has tapped the Boston Consulting Group for a report in Australia Post’s operations, which is expected in coming weeks.

Former Australia Post CEO Ahmed Fahour got his start working with Boston Consulting Group (BCG) as early as 1993, and returned to its venture capital arm, BCG Digital Ventures, after leaving the postal service in recent years.