Ardern said she believed New Zealanders do want change despite Labour stalling in the latest 1 News Colmar Brunton poll and National taking a healthy lead again.
Ardern said the poll showed National and Labour and the Greens (on 8 per cent) together were "neck and neck".
Ardern did not believe the drop was because of Labour's uncertain position on tax policy - or her own decision to back down and rule out introducing new taxes until after 2020.
She said voters she met were more concerned with health and mental health than taxes.
She accused National of "fabricating" claims there was a multi-billion hole in Labour's fiscal plan, despite economists lining up to dismiss the claim.
"I have been out there on the road saying you were a competent Finance Minister, but for you to stand here today...I cannot believe two days out from an election you continue to mislead people like that."
Ardern said English and National had mounted an "unfair" campaign on Labour's tax policies and that had an impact.
"There's no doubt the negative campaign from National has had an effect. That's not going to change the way I campaign."
English denied it was a negative campaign, saying it had every right to question and challenge Labour's policies. He denied his claims about Labour's income tax were misleading, saying Labour would have to legislate to restore income tax rates again.
However, English was also cautious about the poll results, saying he believed the Labour and National blocs were "neck and neck".
"We want voters to consider very carefully the choice they are making on Saturday."
Jacinda Ardern said she believed New Zealanders do want change despite Labour stalling in the latest 1 News Colmar Brunton poll and National taking a healthy lead again. Photo / Getty Images
English said National's rise followed voters getting into the "tin tacks" of the campaign and weighing up what the two parties were offering.
He had predicted in a previous debate that the "stardust" around the elevation of Ardern as leader would settle and voters would start to look more seriously at what was on offer.
Debate moderator Mike Hosking told English the rupture of the fuel pipe to Auckland Airport made New Zealand look like a "huckleberry little nation", and some responsibility had to rest with his government.
English said such accidents happened, and fuel storage capacity was increased five years ago. Ardern said National hadn't spent money to safeguard supply but "apparently we have enough for tax cuts", and Labour would either build more storage or a second pipeline.
Hosking also asked Ardern about her plans to try to renegotiate free trade agreements such as the TPP and the agreement with South Korea to allow Labour to ban foreign property buyers.
Ardern said South Korea had sought a carve-out to stop New Zealanders buying property there and asked English why he had not done the same.
English replied: "We didn't think we'd be able to achieve something like that and it wasn't our policy anyway."
English said New Zealand was a small country that was open to trade and investment. Ardern said she believed it was simply because National had not cared. "Well, I care."
Ardern was also asked about NZ First leader Winston Peters' statement that although he supported charges on water bottling, he would not support water levies on the rural communities.
Ardern said she was committed to implementing the water charges anyway.
Asked if she accepted rural New Zealand was offside with Labour, Ardern said she believed there was unity on the issue of clean waterways. She said farmers were not the main target of the water charges policy.
"I targeted water bottlers. New Zealanders wanted them to pay their fair share, but there is a flow-on effect.
"The vast majority of farmers are not affected by this policy."
Asked if the accumulation of the water tax, the Emissions Trading Scheme and the Green Party's nitrates levy amounted to an attack on the farming sector, Ardern said they were not all Labour policy. She believed it was possible to farm smarter.
"The division we've seen has been stoked during this campaign, but not by me.
"When we lift our brand as a clean green country we all benefit from that brand - especially agriculture because they trade on that brand."
English said National and farmers had already put a lot of work into water quality. He said the water levy was a randomly applied levy and mechanisms such as nutrient allocations and work with farmers was a better option.
He said every New Zealander - including himself - wanted clean waterways. He said a levy on water bottlers would be difficult to implement because it would put a price on water.
Ardern said health was the biggest issue raised with her during the campaign, particularly people who couldn't get help for mental health problems.
"You just have to ask someone who is working in the system...they are working extra shifts, that they don't have enough GPs," Ardern said, saying a GP in Wellington had kept their practice open until midnight to treat a mental health patient because there was nowhere else the person could go.
English was asked about people who were not getting treatment for prostate cancer quickly enough. He said sometimes in a large health system things didn't go as they should, which was why there were safeguards.
"I don't accept that everything that happens in the health system is about a lack of money."
He agreed a new approach was needed on mental health, and National had committed to that, including e-therapy.
On the view from business, Ardern said vision was needed on issues such as the housing crisis. She accused English of allowing poverty to worsen.
"Do we have vision around how to address those, or do we stick with the status quo? Under my leadership there will be no auto-pilot."
English said National had better solutions than Labour, and his party had a strong focus on social issues, including through the social investment approach.
'When they go low, I go high'
Jacinda Ardern said Bill English has damaged his reputation over National's 'fiscal hole' attack. Photo / Nick Reed
Jacinda Ardern has quoted Michelle Obama when asked about National's attacks on Labour's fiscal plan and tax agenda - saying, "when they go low, I go high".
The most heated exchange during the final debate between Ardern and English on TV1 was when English stood by National's assertion that there was a multi-billion dollar "hole" in Labour's fiscal plan. That is despite a number of economists saying that claim is incorrect.
"It was disappointing to see that Bill English continued to follow Steven Joyce's line on that when it has been absolutely disproved.
"I would have thought he would have used the last debate to talk about what he is actually going to do in a fresh government - rather than all the mistakes of the negative campaigning that they have used."
During the debate Ardern told English she had always told people he was a competent finance minister, "but I cannot believe two days out from an election you continue to mislead people like that".
Speaking to media afterwards, she said he had damaged his reputation as "honest Bill".
"I didn't want a negative campaign. I thought New Zealanders probably didn't want to see politics as usual."
Asked if last night's result showed National's attacks on fiscals and taxes had worked, Ardern said regardless of whether that was true, it wasn't a reason to campaign in that way.
"I don't think that really serves New Zealanders and voters particularly well. A negative campaign that is focused more on us than their own ideas probably shows that they are out of ideas."
'The commentators have never done a Budget. I've done eight'
Bill English said on Labour's books, health and education would get extra funding over the next four years but there was little for any other area of government spending. Photo / Dean Purcell
English stood his ground after the debate, saying there was disagreement about the size of the hole in Labour's books but its fiscal plan would result in a "hardline austerity" Budget in many areas.
He said "everyone" agreed with that, but when pushed repeatedly on who agreed, English struggled to come up with a name before finally naming ANZ economist Cameron Bagrie.
English said his own experience as finance minister was more crucial.
"The commentators have never done a Budget. I've done eight. I back myself against commentators who've never done it."
He said on Labour's books, health and education would get extra funding over the next four years but there was little for any other areas, such as police, social workers or conservation.
"They've ended up in this position because they've got a hole in their budget. So when we've got surpluses and a growing economy, they're talking about running some hard line austerity for about a third of what the government does."
Bagrie had disagreed with Joyce's analysis of where the $11.7 billion fiscal hole was but pointed out there was little money left over for any other spending.
