Paid parking for workers in Canberra's Parliament House is 'bullshit' according to a Liberal Senator.

And the National Capital Authority insists that no-one has been over-charged for parking in the Parliamentary Triangle, as a result of recent irregularities in credit card payments.

Senator Bill Heffernan during an earlier Senate estimates hearing. Credit:Andrew Meares

Colourful NSW Senator Bill Heffernan says the impact of paid parking on service workers, who work "bloody hard" at the national parliament, is "horrific".

Senator Heffernan might have been speaking for tens of thousands of public servants and other workers in Canberra's national precincts, who lost their free parking in 2014, when he declared the new regime on Capital Hill was "bullshit", during a Senate Estimates hearing late on Tuesday night.