Singapore (CNN) It's a bustle of activity in the drop-in center. Men line up to sign their names in a book and claim tokens for a free meal, redeemable at cheap restaurants in Singapore's Little India district.

They're all migrants without jobs in the city-state; many are seeking help to reclaim unpaid wages. The drop-in center, run by migrant rights organization Transient Workers Count Too (TWC2), can see up to 500 men each night.

Singapore's constant construction boosts the economy, and relies on a large foreign labor force. As of June 2017, Singapore had about 296,700 migrant workers in the construction industry, from countries like Bangladesh, India, Myanmar and China, according to the Ministry of Manpower.

Working in a city without a minimum wage, they earn a fraction of the salaries of white collar employees who toil in offices the migrant workers construct. Despite the city state's reputation for technocratic efficiency, for some it's a huge struggle to get paid.

Dreams punctured

Sardar Md Insan Ali from Bangladesh hoped his earnings from Singapore's construction sector would translate to a better life for his parents, wife and young child.

He arrived in 2017, and was promised he would be paid S$1,600 (US$1,173) a month.

After his arrival, he said he discovered his wage would be just S$18 ($13) per day. His employer chose not to pay him in full for eight months.

"My boss would only lend us S$200 here, S$300 there [to get by]," Sardar said. The 31-year-old would keep a little money for himself and send the rest to Bangladesh.

Labourers work at a construction site in the financial district in Singapore on August 8, 2014.

This is a familiar tale to Tamera Fillinger, who helps to manage TWC2's Wednesday clinic that assists workers with injury and salary claims.

"What we see over and over again is that the guys will put up with the employer's assurances, for some number of months, that they will be paid the full amount," she said.

"Some guys go months without being paid at all, but most of the time they are shortchanged or underpaid."

"What really pushes them to claim is when the employer stops paying altogether or the guys give up, realizing the assurances are not going to come to fruition."

Singapore's Ministry of Manpower said it had received 9,000 salary-related claims involving about 4,500 employers in 2016. These figures include both local and migrant workers.

According to a response to a parliamentary question by Lim Swee Say, Singapore's Minister for Manpower, 95% of those cases were resolved either through mediation or in the Labor Court. He added that 158 employers had been prosecuted and convicted over the last three years for not paying wages.

However, Jevon Ng, a social work executive at the Humanitarian Organisation for Migration Economics (HOME), said that number is low, because the ministry favors "a conciliatory approach over a punitive one in resolving salary claims" to maintain its business-friendly reputation.

"It has been reluctant to prosecute employers even when there is evidence that employers deliberately undermine the system and cheat workers of their salaries. This gives employers the leeway to exploit workers and will only cause the situation to become worse," he said.

Singapore's Ministry of Manpower said in a statement that it prosecutes employers who willfully refuse to pay workers their owed salaries and said that it has been able to recover salaries in full for 90% of cases.

However, it said it didn't criminalize every case of salary non-payment, especially those borne out of business failure. It said workers who were unable to get back their salaries were able to receive assistance through ex-gratia payments.

An advice center run by migrant rights organization Transient Workers Count Too (TWC2). The man with the striped shirt and beard is Sardar Md Insan Ali. He worked as a construction laborer.

Repercussions

Frustrated with not being paid their full salary, Sardar and two of his co-workers decided in September to complain to the ministry.

Such a move is not an easy decision for most workers. Filing a complaint against one's boss can trigger repercussions. Under Singaporean law, migrant workers' permits are tied to their employers, who can terminate work permits at any time.

Migrant workers typically pay agent or recruitment fees that range from S$3,000 up to S$15,000 to get a job in Singapore, according to a paper released by HOME earlier this year.

Singapore's dazzling skyline has been built with help from foreign construction workers

To pay these fees, some migrant workers have to sell jewelry or land, borrow money from relatives, or take out bank loans, the paper said — all of which adds pressure on the worker to make money once in Singapore.

For that reason, many foreign workers believe it's better to be underpaid than not paid at all, Fillinger at TWC2 says.

His employer canceled his work permit as a result of his complaint, and Sardar was scheduled to be repatriated on October 21 2017. However, the Ministry of Manpower intervened and he's been allowed to stay while his case is pending. That's left him in a difficult situation. He can stay in Singapore, but cannot work.

"The not being able to work is just draconian, because how are the guys supposed to remain in country to follow up on the claim process if they have to pay for their food and lodging, and they're not making any money because they can't work? The employer is supposed to pay throughout this process, but many don't," says Fillinger.

'I have no money to send home'

Singapore's Ministry of Manpower says all workers with valid salary claims are allowed to change employers, but NGO volunteers who have assisted migrant workers say that isn't always possible.

According to the Ministry for Manpower, 600 migrant workers sought a change of employer in the first six months of 2017, but only half found new jobs in Singapore.

South Asian workers play a cricket game on the field next to Little India district in Singapore on December 15, 2013.

"Even in cases when workers are allowed to change employers, workers are already penniless as they would have exhausted their savings from not being paid salaries for months," said Ng.

"This significantly reduces their ability to look for new jobs as employment agencies demand upfront payment of excessive agency fees before agreeing to place them with employers," he added.

The Ministry of Manpower said the law prohibits agencies in Singapore from charging excessive fees, with agencies not allowed to collect more than two months' salary, and no more than one month for each year of service.

The system creates multiple barriers for workers like Sardar. After he spoke to CNN last year, the drop-in center lost track of him and it's not clear whether he was able ultimately to recover his money.

"It's not a good feeling," he said. "I have no money to send home, so my father, who is a farmer, has to take care of everyone."