Labour's SOE spokesman Clayton Cosgrove said Mighty River had responded to just 37 of the 133 questions and the answers received lacked detail.
Other SOEs including Genesis and Solid Energy had responded in detail to exactly the same questions, "rather than being smart alecs".
However Clark's bid to have the hearing postponed - labelled "political grandstanding" by National MP Sam Lotu-Iiga - was defeated.
Clark later told Withers and Dr Heffernan the company had been "smart arses" with their responses and had given a "two fingered salute to the taxpayer" by not responding adequately to the questions. Green Party MP Gareth Hughes described their response as "disdainful".
Withers later told reporters "there was absolutely no intention to treat the committee with disdain". She and Heffernan would go back over the questions.
Heffernan said he'd signed off the responses and believed they did not apply to an SOE.
"If those questions are phrased to us as an SOE we will answer them."
He said the company was not making a big deal about providing information about items such as company credit card details.
"I can tell you right here that we have three credit cards in the company that are held for office administration expenses. No employee has a credit card"
Heffernan said that information was not provide to the committee members "because it wasn't a question addressed to an SOE".
There was "absolutely no intention to thwart the process or to be smart alecs so we'll relook at the questions", said Withers.
Meanwhile, Withers confirmed Mighty River's directors were being paid $1200 each for every day they spent working on the initial public offer.
Withers could provide an estimate of how many days directors had worked on the IPO, but "it has been a busy time for a significant period of time but as I said we have underspent the allocation to the end of last year" and she believed they would underspend the allocation for the remaining period this year.
Cosgrove later said Treasury documents showed the company's directors were paid $190,000 for working on the IPO in the period to November 30 last year alone.
He questioned why Heffernan easily gave information about company credit cards to reporters but wouldn't supply the same information in response to committee members' questions.
Copies of the questions supplied by Labour shoed Mighty River responded to most, including the question about credit cards, by stating: ``Not applicable to Mighty River Power is not a Department, Ministry or associated agency''.
Copies of last year's questions and responses show the company gave a full answer to the same credit card question worded in exactly the same way.
Infographic: Claudia Ruiz