Plumbers, gasfitters and drainlayers are unhappy with the training their apprentices have been getting from the super-institute Te Pūkenga.
They have told RNZ the quality of assessment was poor and frequent block course cancellations meant some apprentices were taking longer than five years to finish their apprenticeship.
But they are not convinced that abolishing the institute, which is trying to amalgamate on-campus, work-based and distance training, will make any difference.
Wellington plumber Mike Gooch said training for his business' four apprentices had him tearing his hair out at times.
He said there had been problems for a long time, but the creation of Te Pūkenga, amalgamating polytechnics and most industry training organisations, made things worse.
"I think it's been a bit of a disaster really. We're not getting the results, apprenticeships are going over, they've got poor facilities, communication is not that great. We were expecting this to be the big new, bright, shiny thing, one polytechnic to rule them all sort of thing and it just hasn't turned out like that at all. I'm really disappointed to be honest. We think the outcomes have gone backwards if anything," he said.
He said Te Pūkenga repeatedly cancelled apprentices' places on block courses, apparently due to a lack of tutors, and as a result, some apprentices were taking longer to finish their apprenticeships.
Plumber Reuben Cutts said his seven apprentices had also had problems.
"The marking of the courses where they lose students' work, they have to go and re-sit stuff, that's happened to a few of my apprentices," he said.
"Some of the course syllabus I think is out of date, they're learning old skills that are just not relevant in today's trade."
But he said the problems had been around since before Te Pūkenga was set up.
"The issues that we see year in, year out have been there for a long, long time to be honest. Whether it's out-of-date syllabuses or just poor tutors," he said.
Dave Strong said his business had five apprentices and some were facing delays because their places on block courses had been cancelled.
He said he received only a couple of weeks' notice of block course dates, which made it difficult to organise business.
However Strong said things appeared to be getting better.
"Since the introduction of Te Pūkenga, it's got worse. I would say it's slightly improving as time goes on and people are trying to put things together," he said.
The plumbers RNZ spoke with said they did not believe that axing Te Pūkenga, as the National Party has promised, would improve the situation.
They worried it would cause more disruption.
Master Plumbers chief executive Greg Wallace said complaints about Te Pūkenga were widespread but the problems pre-dated its creation at the start of this year.
He said part of the problem was that polytechnics had not been able to hire enough tutors to keep up with growth in the number of apprentices and some of the facilities across Te Pūkenga were not up to industry expectations.
Wallace said work was under way to address plumbers and gasfitters' complaints but he was not convinced actions were being taken to address those issues.
Te Pūkenga said it had run 445 block courses so far this year and cancelled only 16, mostly due to Cyclone Gabrielle, with 11 others rescheduled because of low student numbers.
"Cancelling block courses is a last resort for Te Pūkenga. Our national network means that if tutors are unavailable, we can bring in tutors from elsewhere to ensure the course is not cancelled," it said.
"All assessment material requires pre-moderation by an external party and post-moderation is also undertaken. It would be expected that any issues with assessments would be picked up through these quality assurance practices if not raised by a learner or tutor. Any concerns raised about the quality of assessment is taken seriously and is always followed up with the campus management and tutors."
Te Pūkenga said it would develop new training programmes after Waihanga Ara Rau, the workforce development council responsible for the construction sector, finished reviewing unit standards and qualifications for the plumbing, drain-laying and gasfitting industry.
Waihanga Ara Rau said there had been persistent problems but it had a project aimed at fixing them.
It said it had helped 175 overdue apprentices catch up, and reviewed the training providers and the training programme.
The council said it was developing a new programme all training providers would use with assessment in the workplace instead of via block courses.