Some Aucklanders have been offered tens of thousands of dollars less than what their own tradies have quoted.
And they say some insurers are not readily providing their scope of work or assessment for homeowners to compare and negotiate.
Auckland resident Jen Jones has to replace her kitchen, flooring and part of the ceiling after her house flooded in the anniversary weekend storm.
A project manager by trade, she got quotes for the repair work of about $90,000 but the insurer's own scope came in at just over $20,000.
"I was just gobsmacked. The lady on the phone she goes: 'Oh yip, I can see we've had the quote through and it's all been approved so if you're happy I can process that payment today of $24,000'. I think I scoffed, I was like: 'No'".
Jones said the insurer told her their $24,000 offer was a like-for-like replacement.
But the insurer would not provide her with its scope of work for the job so she could compare with her own builder's cost estimate.
"It was all very cagey. I asked them for a scope an they ended up going to the builder and the builder said: 'No we're not going to send our scope, you send us her scope and quotes and we'll look at it and give you feedback'," she said.
"It's like they've undercut it and so don't want you to see it."
Jones has since revised her quote down and the insurer has upped theirs but it was still half what she understood the repairs would cost.
She would lodge a complaint if it was not resolved because insurers were required to release the scope of work they base a settlement offer on.
The Government's claims resolution service was helping people settle problems and so far nearly 550 people have asked for help related to the Auckland Anniversary weekend flooding and Cyclone Gabrielle - of which more than half have been resolved.
The service's director Darren Wright said many relate to the scope of work insurers were providing.
"We're discovering that some of them are actually full and final. So what that can do, in certain circumstances, is transfer the ongoing risk from the insurer to the homeowner," Wright said.
"That is something that we are concerned about and really encouraging homeowners to make sure that they do seek some independent advice."
Auckland builder Lachlan Wilkinson said he has seen some lowball offers from insurers.
His most recent quote was to replace two bathrooms and bedroom jib to dry out the framing, after the house flooded in the anniversary weekend storm.
"We came in at about $100,000 to do all the work with all the outsourced trades and the insurance builders came in at $50,000," he said.
"That's a big gap and there's just no way it can be done for that sort of price."
Wilkinson also said it was hard getting insurers to hand over their scope of work, but when they do he finds they have left out half of what was required for the repair job.
"They sort of sit on those assessments they won't hand them out that easily. When we are getting them we're finding that half the scope's missing as far as the reinstatement goes. The reinstatement is pulling the house apart and putting it back together again once the framing's dried out."
Since the flooding in January, he has been working full time preparing quotes.
"I haven't swung a hammer since the floods. It's very time consuming."
With 100,000 claims lodged so far for the Auckland flooding and Cyclone Gabrielle, Jones said it took persistence to get any progress.
"It's the people who are hounding their insurance companies that are getting any kind of progress and the ones that aren't haven't even had assessors to their properties yet."
Insurers have a responsibility to update customers every 20 business days, until their claim was resolved.
The Insurance Council said insurance companies use market prices and will provide the full scope of works with a breakdown to the customer - and when this was not provided homeowners can request it.
It recommended homeowners seek independent advice before accepting an offer if they have concerns about it, and talk to their insurer about any difference in scope of work.
The Claims Resolution Service offers free, independent advice. The service was helping people navigate insurance claims, providing advice and in some instances case managing on behalf of homeowners.
