A guarantee of two consecutive days off each Christmas for shop workers is to be demanded by Mandate on foot of a motion passed unanimously at the union's conference yesterday.
Delegates criticised the "corporate greed" they claimed was forcing retail employees to work an ever-increasing number of unsocial hours.
Joan Gaffney, of the Dublin distributive and administrative branch, which proposed the motion, said that, at a time when retail outlets were making record profits, shops and stores wanted to make even more money by opening for 24 hours, seven days a week, including St Stephen's Day.
"They have no regard for staff or their families," she said. "We need to make our voices heard and send a clear message from this conference: 'Enough is enough, no more. Christmas Day and St Stephen's Day are off limits'."
Dermot Fay, of the licensed trade division, said that his branch was "100 per cent" behind the motion. The vast majority of workers, he said, had seven to 10 days off at Christmas. "All we are looking for is a miserable 48 hours."
"Employers and the Government, they don't give a damn about us. We are mobile cash registers, human cash registers, and that's all they want out of us," he added.
As well as calling for a minimum two-day consecutive break at Christmas, the motion condemned "the corporate greed which permeates throughout all holiday periods".
Another motion passed unanimously claimed that an increasing number of employers were "willing to engage in the job displacement of Irish workers" in order to maximise profits and gain an unfair advantage over competitors.
The motion claimed there was "more than anecdotal evidence" of employers "wilfully dismissing Irish workers only to employ migrant labour on considerably [lower] rates of pay and poorer terms and conditions".
South-east divisional organiser Bill Kelly said he had first come across this problem when he was contacted by an African man who worked between 50 and 60 hours per week in the retail trade while being paid for only 39 hours. Migrant workers had a "terrible fear" that if they took a stand in pursuit of decent terms and conditions they would be deported, he said.
Meanwhile, the conference heard that Dunnes Stores had agreed to pay all outstanding wages, including a Christmas bonus, to an employee of its Cornelscourt branch. Joanne Delaney was sacked in November for refusing to remove a Mandate badge from her uniform. Ms Delaney was reinstated last month after a campaign on her behalf.