Rowland said that only four out of 91 questions from the 15 June spillover Budget Estimates session were answered on time.

She said 78 answers arrived late, nine were not answered and many of the delayed answers resulted in the NBN Co offering the following response:

“The volume of detailed questions on notice and the limited time available to respond mean that NBN must prioritise questions that are not answered in whole or in part in regular reporting vehicles such as weekly updates.”

Rowland said it appeared that even the Senate had not been spared what she described as the "wrath of the Fifield triangle – a vortex of drift which delays almost everything in its path".

She said Coalition Senator Linda Reynolds, the chair of the Senate Communications Committee, had expressed her frustration at the delay on 24 May, saying:

“I was quite dismayed last night to get, I think, 106 responses arriving when we were here at estimates yesterday for another portfolio between 8.00 and 10.30 last night, which did not give any of my colleagues time to read or digest the answers. It has been two months.”

Rowland said Labor Senator Anne Urquhart had put this in context a day later, with this statement: "“The Finance Department had answered 100% of its 129 questions on time. Prime Minister and Cabinet had answered 73.6% of its 229 questions on time. The Department of Foreign Affairs had answered 98.7% of its 154 questions on time…. Yet NBN Co only answered 11 of its 145 question by the due date. This amounts to NBN answering a meagre 7.5% of its questions on time.”

Rowland said on Tuesday, Communications Minister Mitch Fifield had been asked to explain himself in the Senate and could not provide a definitive date on when responses to the remaining questions would be released. 

"The minister then upped and left, and relied on Senator Ian MacDonald to assist in explaining his tardiness. You can imagine how that went," she said. "This slow and unreliable approach to the Senate mirrors the experience of Australians on the copper NBN.

"Labor calls on Minister Fifield to get his act together, and ensure the Senate receives timely responses to assist with its oversight of this important $50 billion infrastructure project."