Hundreds of lecturers on an hourly rate at Cardiff University are working without contracts, and some have not been paid since the beginning of the academic year.
New conditions for the employees were introduced at the start of the term, when Cardiff said that all hourly paid staff would have contracts by Christmas.
Those affected are paid more under the new deal, but 100 part-time lecturers were made redundant from Cardiff's Centre for Lifelong Learning in anticipation of the increased costs.
Although the contracts should have been introduced in September, many of the 600 staff affected are still waiting, with some yet to be paid.
Todd Bailey, lecturer in psychology and branch president of the University and College Union, said he knew of at least three staff who were still owed pay from September.
"Although the university says it has arrangements by which they can put in monthly claim forms and be paid, at least some staff who have contacted me were unaware of this and haven't been paid yet," he said.
He claimed that the cases he knew about were likely to be "the tip of the iceberg".
The university's human resources department has told the UCU that some contracts had been delayed because of the need to calculate the hours staff worked in previous years.
One lecturer affected, who did not wish to be named, said: "We still haven't got a clue as to how much we're getting paid, or when or if we're getting paid. I'm unwilling to keep working under such murky conditions for much longer."
A spokesman for Cardiff said the delay in issuing contracts was partly the fault of the UCU for failing to accept permanent contracts for hourly paid staff in 2008.
He said that more than 400 contracts had already been issued, and a "small number" were still being discussed.
"Interim payments, including temporary contracts, were put in place while these individual discussions continued ... Some members of staff made a personal choice to delay payment until they received their final contract," he added.