Plumbers, gasfitters and drainlayers are unhappy with the training their apprentices have been getting at the super-institute Te Pūkenga.
They say the quality of assessment is poor and courses are often cancelled, meaning some people are taking longer than five years to complete their apprenticeship.
Sector leaders say the problems pre-date Te Pūkenga and they're working on fixing them.
Education correspondent John Gerritsen reports.
