London CNN  —  More than a year after Shein promised to tackle excessive working hours in its supply chain, a new report suggests the Chinese fast-fashion company still has a problem. Workers in some factories supplying Shein are still working 75-hour weeks, according to an investigation by Public Eye, a Swiss human rights advocacy group that first highlighted the alleged abuse back in 2021. “The 75-hour weeks that we found out about two years ago still seem to be common at Shein,” the Swiss organization said. Public Eye interviewed 13 textile workers employed at six factories in Guangzhou, a region in southern China, last summer. It found that staff worked an average of 12 hours a day, excluding lunch and dinner breaks, and usually for six or seven days a week. Shein does not reveal the identity of its suppliers, Public Eye said in its report. The group said it established that the factories were Shein suppliers through interviewees’ responses as well as the presence of Shein products. Public Eye also claimed that workers’ wages had hardly changed since its 2021 report. They fluctuated between 6,000 and 10,000 yuan per month ($829 and $1,382). However, after deducting pay for overtime, wages fell to about 2,400 ($332) a month. That’s well below the 6,512 yuan ($900) Public Eye says is a living wage in China, citing calculations by campaign group the Asia Floor Wage Alliance. “I work every day from 8 in the morning to 10.30 at night and take one day off each month. I can’t afford any more days off because it costs too much,” Public Eye cited one worker as saying. Shein is an online shopping retailer founded in 2008 that sells its cut-price fast fashion apparel all over the world. Shein said in a statement to CNN that it does “not recognize many of the allegations in (Public Eye’s) report.” “The Public Eye report is based on a sample of 13 interviewees and, though all voices in our supply chain are important, this small sample size should be seen in the context of our comprehensive ongoing process to continually improve our supply chain, which involves engaging with thousands of suppliers and workers within the supply chain,” it added. The company said in its statement that was investing tens of millions of dollars to strengthen the governance and compliance of its suppliers. “We will continue to make substantial investments in these areas.” In December 2022, Shein announced plans to invest $15 million to upgrade hundreds of factories belonging to its suppliers. That announcement followed a documentary broadcast by the UK’s Channel 4 that made allegations of labor exploitation against two of Shein’s suppliers in China, with factory staff allegedly working 18 hours a day and making pennies per item. “These efforts are already delivering results, with our regular supplier audits showing a consistent improvement in performance and compliance by our supplier partners,” Shein said Monday. Public Eye said that Shein’s code of conduct for suppliers states that staff must not work more than 60 hours per week, including overtime, and should have at least one day off a week. The advocacy group said it did not return to Nancun, the location of Shein’s headquarters and interviews it conducted for its 2021 investigation, because an increase in media scrutiny in the area made “the atmosphere too risky.” Some workers also told investigators that they had noticed an rise in the number of surveillance cameras in the factories, and believed that the recordings were sent to Shein in real time to help the firm enforce its rules. Public Eye’s investigators also observed young people, judged to be about 14 or 15 years old, performing simple tasks, such as packaging, in some of the factories. Juliana Liu contributed reporting.