You have to hand it to Nathan: benefit-sanctioned, hungry, and waiting weeks for the renewal of his universal credit payment, he takes the dog out into the fields and catches himself a rabbit for dinner. Back at home he and his partner, Abbey, skin it. They eat rabbit soup, the dog gets to chew on the rabbit head. There may be few jobs, the dole doesn’t stretch far, and the price of baked beans has gone up; but starvation can be held at bay, he reckons, if you are prepared to hunt wild animals.

David, 40, is also sanctioned. He’s partially blind, and his GP said he shouldn’t work. The Department for Work and Pensions (DWP) decreed that he can work, and stopped his benefits after he missed a jobcentre appointment (which he says he didn’t know about). He’s got £5 to last him for the month. He can’t afford a phone so he calls universal credit from the phone box in the street, sobbing as he’s put on hold, listening to the endless, infuriating loop of Vivaldi’s Four Seasons. “It’s inhuman,” is how he describes his treatment by the DWP. “I feel like a bear that’s prodded with an electric volt; a fucking dancing bear.”

Nathan and David appear in a three-part Channel 4 documentary Skint Britain: Friends Without Benefits, starting on Wednesday, which examines the impact of universal credit on a group of claimants in Hartlepool. There are no surprises for anyone who has followed its chaotic rollout. The film’s subjects encounter distant, glacial bureaucracy; long waits for benefit payment; capricious, impoverishing sanctions; and practically no backstop against destitution.

‘The work and pensions secretary, Amber Rudd, claims the new system is ‘fair and compassionate’ and the bad press it gets is ‘down to one or two particular individuals’.’ Photograph: Stefan Rousseau/PA

It’s a timely reminder of the real-world, human impact of universal credit. The work and pensions secretary, Amber Rudd, claims the new system is compassionate (even though she now admits it drives food bank use) and the bad press it gets is “down to one or two particular individuals”. The DWP likes to say universal credit works well for most claimants, that it proactively fixes “teething problems” as they emerge. Its

own claimant survey, published last week, tells a different story. It finds that one in five claimants weren’t happy with their experience of the new benefit, while one in 10 reported they were “very dissatisfied” – equivalent at the time to 60,000 claimants (it would be now nearer 140,000). That’s not most claimants; but it is a high margin for error (and this survey was before the more complex “full service” cases were fully accommodated).

The DWP’s claim that it is on a constant roll of “test and learn” also feels unpersuasive. It has made relatively minor changes designed to make the system more manageable for claimants, often when under the full glare of the media and backbench Tory MP concern, or when a judge rules that the policy it has hitherto been pursuing with implacable determination is unlawful. Politically, the DWP tone has changed from shrill denialism to Rudd’s more equable and conciliatory approach, where at least there is an apparent recognition (as you would hope from an MP whose Hastings constituency has keenly felt the trauma of universal credit) that there are good reasons why the public has very little confidence in universal credit.

Trevor, Tamsyn and Tracey from Skint Britain: Friends Without Benefits. Photograph: Richard Ansett/Channel 4

But will Rudd go beyond piecemeal reform? So far, makeshift changes have had little effect. As Citizens Advice (CAB) pointed out this week, tweaks to universal credit in the 2017 budget have made a “dent” in the problems, but not much else. Half of claimants who came to the CAB were at risk of eviction (many more than under the previous benefit system), with similar proportions in debt or struggling to eat or pay bills. Last month the high court ruled that universal credit’s “odd” and “nonsensical” policy of rigidly enforced assessment periods, which can leave some working claimants hundreds of pounds out of pocket and reliant on food banks, is unlawful. It will take more than tinkering to solve this problem at the structural heart of universal credit.

The big, fundamental flaws of universal credit remain: five weeks is far too long to make low-income claimants wait for payment because it drives debt and rent arrears; too many claimants will be worse off when they move on to universal credit (many without transitional protection); and the already miserly level of benefits, frozen now for nearly three years, is simply not enough for people to live on. Universal credit is intended to be a lifebelt, but is too often a deadweight, dragging people under.

In the documentary, single mum Terri is looking for work after years spent caring for her daughter. It’s not easy (she’s on universal credit). She pops in for a bit of guidance from Linda, a fortune teller. “I’m not going to paint your life as a bed of roses, sweetheart, because it hasn’t been,” the urban seer divines. “So I’m going to wish you all the luck in the world, because, I’m going to be honest, you need it.”

• Patrick Butler is the Guardian’s social policy editor