Workers whose bosses failed to pay the National Minimum Wage are to be refunded a record £2m, the government has revealed.
In its latest "name and shame" campaign, it lists 230 employers which have not complied with the law.
In total 13,000 employees have received - or will receive - compensation for their loss of pay.
Among the worst offenders was the retailer Argos, as well as hairdressers and beauty treatment businesses.
About 50 employers in the hospitality sector - including two fish and chip shops - were fined for not paying the minimum wage, or the National Living Wage for those aged over 25.
However the largest fine, of £800,000, was levied on Argos.
In February Argos admitted failing to pay 37,000 staff an average of £64 each. However, only a third of those are included in the latest figures, as the others were no longer working for the company at the time.
Employees had been required to attend briefings before their shifts started, but without being paid. They also had to undergo security searches after their shifts ended.
Sainsbury's, which bought Argos a year ago, has already apologised for the mistake.
"I am pleased to say the issue was resolved quickly, and processes have been updated to ensure this cannot happen again," said John Rogers, the chief executive of Argos.
Despite the government's apparent success in cracking down on pay, it is thought that hundreds of thousands of workers are still not getting their legal entitlement.
In October last year the Office for National Statistics (ONS) said the number of people whose pay was below the headline rate of the NMW was 362,000.
However that number includes workers whose pay levels are perfectly legal. For example, those who have accommodation or other benefits supplied as part of the job.
The TUC said the problem was still far from being solved.
"We know there are more wage-dodging employers out there," said Frances O'Grady, the TUC's general secretary. "TUC research suggests there are at least a quarter of a million workers being cheated out of the minimum wage."
The current rate for the National Living Wage is £7.50 per hour.
The adult rate for the National Minimum Wage is £7.05 for those between 21 and 24.