Think of your favourite gadgets and appliances, and it’s likely some of them started life in a rundown, mosquito-infested dormitory complex an hour’s drive from Malaysia’s capital, Kuala Lumpur.

In each block there is a makeshift kitchen, a small, grubby toilet and three rooms crowded with bunk beds. There is no air conditioning to break the oppressively humid air. Outside, burning rubbish sends acrid fumes through the labour camp, which is strewn with broken furniture and an abandoned vehicle.

To call it a slum would be generous. I’ve seen some truly appalling workers’ camps in Malaysia and the Gulf, but this rivalled the worst.

Every day, the men who live here work on factory lines making components used by Samsung Electronics, one of the biggest electronics companies in the world. Last year, Samsung made a profit of almost $50bn (£38bn).

In Malaysia that money is made largely by the hands of cheap foreign migrant labour – millions of workers drawn from the region’s poorest countries.

Malaysia, where forced labour – a form of modern slavery – is commonplace, has a reputation for the flagrant abuse of workers rights.

But that hasn’t stopped Samsung, and dozens of other leading electronics companies, from setting up shop here.

Unlike its competitors, most of Samsung’s products are assembled in-house, but it uses a long chain of suppliers to provide it with parts, services and labour, including foreign migrant workers.

I walked around the camp, stunned. Why must men who are part of the supply chain of one of the world’s biggest electronics companies live in such squalor and be treated so poorly?

What was so frustrating was that I’d seen it all before. Two years ago, I travelled to Malaysia to investigate the treatment of these foreign migrants working at Samsung.

Men employed by a sub-contractor, but working on the assembly line of Samsung’s microwave oven plant, told me that their passports had been confiscated, that they were being paid less than promised, and that they were deep in debt after shelling out high fees to recruitment agents in their home country.

Despite working at seemingly normal factories, these men were effectively trapped in their jobs by debt bondage and felt unable to leave even though they knew they were being exploited.

Samsung’s response was quick. They fired the sub-contractor and announced improved guidelines for the recruitment and treatment of foreign migrant workers. The guidelines, which apply to Samsung worksites and its suppliers, state migrant workers should pay no recruitment fees, receive the minimum wage and retain their passports.

Samsung said: “We will be strictly applying and implementing these guidelines across our global operations as well as among our suppliers.”

In September, I returned to see if they had lived up to their promises.

At first, there were some positive signs. Workers at the microwave plant told me the factory was safe, the food was good and they liked the games room in their hostel. Some said they were only being paid a basic salary of about a pound an hour, but they seemed satisfied. Most importantly, those recruited directly by Samsung since 2016 said they had not paid any recruitment fees.

Foreign migrants employed by a supplier to work at a Samsung plant in Malaysia live in cramped accommodation, with mattresses on the floor for beds. Photograph: Pete Pattisson

Although it was encouraging to see that changes had been made at this one plant, I wanted to see if the same applied for workers further down the supply chain. Samsung certainly appeared to have made sure that conditions for the men it directly employed and were legally responsible for had improved, but what about the many others also working at this factory, who were instead hired through sub-contracting companies? According to its own guidelines, and international labour standards, Samsung is responsible for their welfare too.

So I went back to the factory and followed a group of men heading home on foot at the end of their shift. Dozens of pairs of shoes crowded the entrance to a couple of flats in a rundown apartment block, within sight of the Samsung plant.

The flats were home to 21 men from Bangladesh. All had been hired by a company that supplied workers, through another company, to Samsung.

They told a very different story. They said they paid vast sums to come to Malaysia, some as high as £3,500 – more than three times the annual per capita income in Bangladesh – but were earning less than promised.

Aminul (not his real name) said it would take him about two years just to pay back the loan he took to afford the recruitment fee. “It’s a huge pressure for me to pay back the debt … When I got here, I realised I made a mistake.”

But like all the men, Aminul says he cannot leave.

“My employer has my passport, so if I want to go back home, I can’t,” he said.

Another group of men, working as cleaners at the same Samsung plant, claimed the company that directly employs them was illegally deducting almost a fifth of their basic salary each month, meaning they were earning far below the minimum wage.

Even at Samsung’s flagship plant in Malaysia, which produces batteries for its bestselling mobile phones, Samsung continues to use sub-contracted workers who have paid high recruitment fees. “They didn’t ask us how much we paid to come here … so there’s no question of us being repaid,” one worker told me.

What was striking was how afraid everyone appeared. They worried that if they spoke to me they would be deported or punished. One worker, referring to his direct employer, told me: “If they know I gave you an interview, they will take me to some place and beat me up.”

When I put my findings to Samsung, they responded with a statement: “We will conduct thorough investigation on this matter that you have shared with us. As a committed member of the global community, Samsung will continue our efforts to both respect and protect human rights of the migrant workers.”

While an investigation is of course welcomed, Samsung could have easily found this out for themselves if they’d really wanted to.

I had a small budget, a couple of assistants and no official access and yet, within a few days, I had uncovered a raft of abuses that strongly suggest forced labour continues among workers employed by some companies supplying labour, parts or services to Samsung.

What I found on my brief journey down this tiny part of Samsung’s electronics supply chain in Malaysia remains an everyday reality for the millions of migrant workers across the world who toil daily to make the gadgets we use to make our own lives easier and more enjoyable.

This is what is looks like when companies are left to police their own supply chains; when mega-companies chase profit, with insufficient concern for a workforce that case has no means of comeback.

What I found in that labour camp is not an inevitability. It is a choice that companies are making. And we all have to bear some responsibility when we look the other way.

Samsung used to have a brand campaign with the slogan: “With Samsung, it’s not that hard to imagine.”

What I’d like to do is ask Samsung and all the companies around the world who rely on the sweat and toil of a migrant workforce to imagine that everyone in their supply chain is their responsibility. Imagine recruiting them directly, not through agents, and at zero cost. Imagine auditing your whole supply chain regularly and rigorously. Imagine paying everyone a decent wage. And then make it a reality.