Drivers at a Stobart depot in Staffordshire say they have been affected by persistent problems with the firm's payroll system, including not being paid at all on some pay days.
A worker at the Hanchurch, Stoke-on-Trent site, who did not wish to be named, says about 70 drivers have been affected by the problems, which have included payments of as little as £6 being made on some occasions.
Stobart says the problems are related to the integration of James Irlam Logistics - which it bought last March for £60m - into its business.
A Stobart spokeswoman says: "This affects only a very small percentage of the group's 5,000 employees. The company is working hard to address these issues and extra resources have been drafted in.
"Working with employees, the group will resolve matters as quickly as possible."
Simon Green, regional industrial organiser for the union Unite, says: "The workers are very upset and angry that their pay has been messed about with."