The short version of how a visa scam got people into New Zealand - and into massive debt.

ANALYSIS: Remember the opening scene of Once Were Warriors? A textbook image of an island paradise filled the screen, before the camera panned back to reveal it was merely a billboard in the middle of a grim urban reality.

New Zealand seems to sell itself to the world in the same way. Are we promoting the false vision of a beautiful, incorruptible country offering a top-class education and opportunities to make your fortune?

After months of investigating visa frauds at the heart of our immigration system, we're convinced it's broken. Corruption and exploitation run almost unchecked. Our newest arrivals are told that fraud and graft are acceptable and unpunished. Scammers operate almost openly, safe in the knowledge they won't be prosecuted.

Our stories initially focused on restaurateur Gurpreet Singh, who for some years appears to have run schemes where he charged up to $35,000 for visas to Indian migrants desperate to stay in this country. Gurpreet has operated thus far without any action from Immigration NZ which, by their own admission, has known some of what he was up to for four years.

But Gurpreet, if he cared at all about the exposure, was unlucky. There are any number of other chancers out there running exactly the same scheme as him.

Here's what else we found: lots of people know it goes on, and lots of people are angry about it.

After our first story, the emails began arriving, and they haven't stopped. Lots were from other migrants trying to tell their stories.

We could only investigate a fraction; and frankly, many were the same, just with the names changed. We chased some down, and found them to be true. In all cases, the villains had never been punished - and yet we were able to establish fairly quickly exactly what they were up to.

The basic scams they run are:

* The Fake Job. There's the paperwork to satisfy Immigration NZ and a salary paid to satisfy the IRD, but the job doesn't exist and the migrant has to return the salary in cash (and top it up for the tax that's been deducted).

* The Underpaid Job. They might tell Immigration NZ and IRD that they're paying minimum wage - but the migrant is either returning some of their salary, or working a huge number of extra hours for free, or for cash under the table and below the minimum.

* The Inflated Job. The real job might be washing dishes - but when it comes to the paperwork, it's a manager's position.

DAVID WHITE/STUFF The Kingpin: restaurateur Gurpreet Singh was the focus of our investigation.

We've talked to countless migrants who came here thinking they would get residency and a well-paid job. Almost all studied for meaningless qualifications purely to secure visas, worked in low-paid, unskilled jobs, and were ruthlessly exploited, usually by other, earlier-arriving migrants, who drained them of their cash. One confessed overstayer claimed his bosses in the kiwifruit industry broke his legs when he fell out of line, knowing he'd never be able to go to a hospital for treatment because he risked deportation.

Yet more emails came from Kiwis with tip-offs about the healthcare industry, hospitality, supermarkets, fruit-picking, IT. Some were angry, most resigned, several had contacted Immigration NZ and felt they'd been fobbed off. There was the kiwifruit orchardist, who wrote about the migrant labour gangs paid below minimum wage and in poor conditions who begged: "Immigration NZ needs to be much more aggressive, relentless and have the ability to impose more substantial penalties."

Or the supermarket manager, who wrote after our story about Gurpreet's proposed sideline in selling marriage visas, that "marriages for sale" was a practice "rampant" in his industry, one which he'd seen painfully unfold several times, with payments of up to $60,000 going from young men to Kiwi women to secure citizenship by marriage: "It is a very sad situation that I have often wished to bring to the attention of New Zealand."

In industries like fast food, liquor stores, gas stations, restaurants and fruit-picking, the reality is that corrupt employers have a huge business advantage because they can massively underpay their staff. It leaves legitimate employers with a choice: do the same, and compete, or stay legal, and face going bust.

As one insider says: "If it looks too good to be true, it is." If a business is winning in its sector but you can't see why, it could be because it's making a huge saving on labour costs.

The cost to society of all this? Beyond the human stories of an underclass of the underpaid denied their rights, there's the pain for those who refuse to break the rules, and there's the loss of tax income that damages us all.

ALDEN WILLIAMS/STUFF Immigration advisor Malkiat Singh says immigration fraud is now "generational".

Immigration advisor Malkiat Singh describes the situation now as "generational exploitation". Each new wave of migrants is exploited, accepts that's how it works, and in turn, once established, goes on to exploit those that arrive after them. For some, it appears, their major source of income is simply from charging newcomers for visas and fake jobs.

Among the cases we've investigated was one where a migrant who had paid for a visa and a fake job tipped off Immigration NZ two years ago; Immigration NZ only began investigating after we asked them about the case. Our conclusion is that Immigration NZ, as it stands, is incapable of halting the tide of corruption.

Why? After years of no political priority being placed on pursuing and prosecuting offenders, they seem hopelessly understaffed. There are less than 30 immigration investigators in New Zealand. Instead of chasing down every case of fraud, it appears the department has wisely tried to focus on landing a few bigger cases to act as a deterrent to the smaller fish; but that tactic means many go unpunished and a culture has sprung up among migrant communities that it is fine to buy your way into New Zealand.

There does finally appear to now be some political will. Immigration Minister Iain Lees-Galloway has changed some visa classes, so they are no longer tied to an employer. He's added extra resource to the Labour Inspectorate, which handle some of the investigatory work, and he's commissioned Auckland University-led research into the issue of exploitation and how Immigration NZ can better police it. He says: "We have inherited a situation where we don't really have a good grasp on the extent of migrant exploitation in New Zealand."

DAVID UNWIN/STUFF Immigration Minister Iain Lees-Galloway says his efforts to clean up immigration fraud are from a "standing start".

Lees-Galloway says the previous government allowed for a huge increase in temporary visas and migrants in low-paid jobs without adding resources to prevent their exploitation. "We are starting from a standing start … but it is an area which is a priority for us."

He denies it's open season for fraudsters, saying the Labour Inspectorate and Immigration NZ are "incredibly vigilant". But when they do catch scammers, only rarely are custodial sentences handed out. Former immigration minister Tuariki Delamere says only harsher penalties - including deportation - can have any impact.

If two journalists, without the investigatory powers or resource of a government department, can unearth and expose a string of such schemes - and we heard of many, many more we didn't have the time to pursue - it's clear that they are everywhere, and not hard to find.

The remote prospect of prosecution has made men like Gurpreet Singh brazen.

New Zealand sells migrants a dream: a reasonably-priced, high-quality education that will, in our own words, be a "pathway to residency", the chance to live here permanently in a skilled job. Our official website tells them it will be "the time of their life". One union organiser, First Union's Mandeep Bela calls this "education trafficking".

Melanie Earley Union official Mandeep Bela calls it "education trafficking''.

Too often, it appears, the qualifications are worthless, and the work they end up in is underpaid, unskilled and exploited. Of course they are breaking the law when they pay for a job - but do they have a choice, other than to return home? Trapped first by pride and then by debt, they stay, but it's hardly the life they were sold, and it's hard to find a benefit for them, or for us, in them being in New Zealand.

Lees-Galloway told us he didn't want New Zealand's reputation offshore to be tarnished. The evidence suggests it already has.