“We don’t ever stop working, not to eat or even to go to the toilet,” says Carolina Martín, a hotel chambermaid in Seville, southern Spain. “We’re the invisibles of the hotel, the last in line and the worst paid. When we first started telling hotel clients what was going on, they were shocked – they’d never spoken to a chambermaid before.”

The consternation concerns a level of exploitation that Spanish trade unions describe as semi-slavery, mainly due to outsourcing. But Spain’s estimated 100,000 chambermaids are fighting back and have used social media to organise themselves as Las Kellys, a play on las que limpian, the women who clean. Their slogan: get organised if you don’t want them to organise you.

Under labour reforms passed by the rightwing Popular party government, the cleaners have seen their wages cut by as much as 40% and their workload increased as hotels outsource their jobs to agencies.

“Before the law was changed, for any outsourcing to be legal the companies had to offer better conditions than those laid out in the convenio [the regional sector agreement],” says Isabel Cruz of Las Kellys in Barcelona. “Under the reform, a company agreement no longer needed to be better, and hotel chains saw an opportunity to cut costs. By outsourcing they no longer had to hire and fire, or pay sick leave or maternity leave.”

Under most convenios, the women are paid €1,200 (about £1,050) a month for a 40-hour week. Cruz explains that, while the outsourced contracts often appear to offer the same conditions, there is a catch: while the contracts specify a rate per six-hour shift, they also specify how many rooms have to be done in that time, on average between 25 and 30, which is not humanly possible. As a result, the women put in unpaid overtime in order to meet their quota, bringing their hourly rate down to €3 or €4.

“If the women stick to their hours and don’t meet their room quota, they’re sacked. Most of the contracts are short-term, so they’re simply not renewed and the woman is blacklisted,” Cruz says.

“We have to do 25 to 30 rooms in six hours,” says Yolanda García, a Kelly in the resort of Benidorm. “But many rooms have four beds in peak season, and this means making up to 85 beds. When they put in extra beds for children they charge a supplement, but we get paid the same. We calculate that in many cases women are being paid €0.89 a room.”

“All the outsourced contracts are for 32 hours, not 40,” says Paqui Martínez, 54, a chambermaid in Mallorca for 11 years. “So they earn €700 to €800 for the same amount of work.”

The groups, which picket offending hotels and organise meetings to raise public awareness, are demanding an end to outsourcing and that all hotels adhere to the convenios. They complain that they receive little support from trade unions. “It doesn’t help that very often in hotels your union representative is also your immediate boss,” says García.

Fear is a big factor, García says. “A lot of the workers are Latin Americans and eastern Europeans, and they are more afraid than local women of demanding their rights. There are many single mothers, so we’re talking about a group who are vulnerable and easy to exploit.”

All the women complain of health problems, such as back pain and arthritis, and many say they only get through their shift on a diet of painkillers. The hoteliers refuse to recognise these conditions as work-related, they say. “In the long run the hoteliers aren’t doing themselves any favours, because it is not possible to maintain standards under these conditions,” García says.

No one from the Barcelona Tourist Consortium or the Barcelona Hotel Association was available for comment.

It is not as though the Spanish tourist industry is struggling. In 2016, a record 75 million people visited Spain, with even more forecast for this year, and hotel occupancy is also at a record.

Take the NH Hotels chain, which manages 131 hotels in Spain. According to its annual report, from 2014 to 2016 its profits in Spain rose by €76m, while the average daily room rate rose by 9.2%. And yet it was one of the first to embrace outsourcing, making hundreds of hotel workers redundant.

In a statement NH Hotels said that outsourcing was necessary to cope with fluctuating demand, adding that “the company takes all necessary means to guarantee the rights of outsourced workers and that companies that failed to comply would lose their contracts”.

Not all hoteliers outsource, however. “Chambermaids are a key part of the core business,” Anna Castán, manager of the four-star Hotel Barcelona Catedral, told a meeting of Las Kellys. “Outsourcing has destroyed working conditions.”

Yet there have been victories, notably in Seville, where women denounced an outsource company that for four years had been charging hotels €1,450 for a service for which they paid the women €601 on the grounds that they were trainees. The company was fined €2.6m.

“This summer we’re planning a campaign to name and shame hotels that employ people in inhumane conditions and also promote the ones that use good practices,” says Cruz. She adds that they are encouraging guests to add comments about working conditions in their reviews on TripAdvisor and similar sites.