"The provision of inaccurate and incomplete information in my initial investigation is unprecedented during my (16 years) as commissioner," Information and Privacy Commissioner Ann Cavoukian wrote in a followup to a report on the deleted emails she released two months ago.
"I am left with the inescapable conclusion that they did not take my investigation very seriously."
Cavoukian issued a scathing report in June which found Liberals in former premier Dalton McGuinty's office broke the law by deleting all their emails on the cancelled gas plants in Oakville and Mississauga.
The privacy watchdog was told at the time that the deleted emails could not be recovered, but it turned out there were ways to get the data back, and the Ministry of Government Services has since unearthed another 39,000 gas plant documents.
"I remain saddened at the failure of (ministry) staff to dedicate adequate resources to provide accurate and complete information to my office," wrote Cavoukian in her addendum released Tuesday.
"As a direct consequence of the incomplete response, the public has been misled...about the ability of staff to retrieve potentially relevant information."
Opposition members of the justice committee, which is holding public hearings into the cancellation of the gas plants, said they were not surprised the privacy commissioner had trouble getting the documents she requested.
"What we had in place under Dalton McGuinty has continued under Kathleen Wynne, that getting at the heart of this scandal is not something that's a government priority," said NDP energy critic Peter Tabuns.
"Obscuring it seems to be the government priority, and the information and privacy commissioner was just another victim of that approach."
The Progressive Conservatives said Cavoukian ran into the same obstructionist tactics that the committee has faced as it pushes for correspondence on the decisions to cancel the gas plants and Liberal attempts to delay release of related documents.
"The committee had either been led around by the nose or allowed to let our wheels spin, and I think they treated the privacy commissioner's request in exactly the same way," said PC energy critic Vic Fedeli.
Earlier Tuesday, William Bromm, legal adviser to the powerful Cabinet Secretariat, testified Wynne had been one of four cabinet ministers who signed an arbitration agreement with TransCanada Enterprises over the cancellation of the Oakville gas plant that still allowed the huge energy company to sue the government.
"This particular package was a 'walk around,' said Bromm. "It was outside of the normal cabinet process, so four ministers signed as the quorum of cabinet and two weeks after this the item would be reported into cabinet as an information item."
David Phillips, a former director in McGuinty's office, rejected opposition suggestions that there had been a conspiracy among senior Liberals to delay the release of the gas plant documents to the committee.
"I never received any order to obstruct anything," he said.
The NDP wanted to know about a list of options Phillips drafted for the Liberals' to deal with another committee's demands for gas plant correspondence in which he talked about "successfully managing the timing and manner of the release of these documents to limit the negative communications."
"This was all about damage control, and that's what prorogation was about as well," said New Democrat house leader Gilles Bisson, who criticized Phillips for boasting in an email about how the Liberals successfully "filibustered" for hours on the issue.
"The prorogation was about trying to duck out on your responsibilities as a government to do what you were charged to do and that was to release those documents when requested."
"No sir," said Phillips. "I disagree with your characterization."
McGuinty prorogued the legislature and resigned as premier last October, just hours before the committee hearings into the contempt motion and the cancellation of the gas plants were to begin.
The opposition parties say the government cancelled the planned gas-fired electrical generating stations in Oakville and Mississauga to save Liberal seats in the 2011 election.