NBC is demanding a ratings redo going back seven months, The Post has learned.

The Peacock network plea comes after Nielsen, the TV industry measurement firm, released reworked ratings for the fall TV season that increased NBC ratings — while lowering audience size for ABC.

Nielsen admitted last week it had botched ratings results since a software upgrade in March — but would re-issue corrected ratings only for the fall TV season beginning Aug. 18.

The incorrect results issued prior to Aug. 18 were insignificantly different from the correct results to matter, Nielsen said.

NBC was not buying it.

The Comcast-owned network wants to know why Nielsen isn’t looking into potential errors that seem to have been handing ABC big wins for months, a source close to the matter told The Post.

The revised numbers released Tuesday could swing millions of dollars of ad revenue among the networks.

Nielsen’s fumbled ratings allowed ABC’s “World News” to capture the No. 1 position in total viewers from NBC’s “Nightly News” during the week of Sept. 29.

It was the first time in 265 weeks that “Nightly News” anchor Brian Williams did not finish No. 1.

But the corrected ratings show Williams drew more total viewers than “World News” — 8.28 million vs. 8.11 million — after NBC gained 33,000 viewers and ABC lost 303,000.

“We are pleased that the corrected numbers confirm that ‘NBC Nightly News’ is the No. 1 news broadcast in America, and has been for the last 265 weeks,” NBC News said in a statement.

The errors are a huge blow to ABC News’ collective ego.

Anchor David Muir and former host Diane Sawyer were seen celebrating the win over NBC in photos on TVNewser.

Staff also got lunch on the house as part of the “across-the-board” win.

ABC, under the corrected ratings, still held the ratings lead within the coveted 25- to 54-year-old demo.