Customers of an Ayrshire trader say they feel ripped off after paying tens of thousands for building works that were not completed.
Russell McMaster, who traded as Alex McMaster Builders and VJL Builders, was paid at least £220,000 for seven home renovation contracts over two years.
But his clients said the works were left largely unfinished and have called for him to be prosecuted.
Mr McMaster told BBC Scotland News he was unavailable for comment.
It comes as Advice Direct Scotland - which offers consumer advice in partnership with Trading Standards and the Scottish government - said complaints about building scams increased by nearly a third last year.
Chris Jardine sleeps in a bedroom which looks more like a building site after the tradesman he hired took his money and never finished the work.
The 46-year-old can see the frost on his breath when he wakes up on a mattress on the floor of his unfinished loft conversion in Bridge of Weir, Renfrewshire.
Mr Jardine had been living in Japan, but returned to Scotland to raise his two children and wanted to convert the loft in his house to create more room for his family.
"It was just after lockdown and it was really hard to get a builder to even return our calls," he said.
"We were aware material prices were going sky-high so we thought if we don't do this now, chances are we're not going to be able to do it at all."
He found Mr McMaster online, who was trading under the name VJL Builders and quoted £35,000 for the work.
It was less than other builders had quoted, but within Mr Jardine's budget, so a contract was signed and work began in July 2022.
Despite a promising start to the job the builders and tradesmen began to turn up less and less, yet Mr McMaster continued to ask for money.
"I didn't want to be the reason they stopped working, which is what they were making me feel like - 'If you don't give us money we can't get folk out to do the work'," Mr Jardine said.
By December 2022, McMaster's builders had stopped showing up completely.
He said: "We eventually had to hire another to come build stairs into the loft as all we were left with was a gaping hole."
In total Mr Jardine paid £31,500. A separate tradesman estimated the value of the work completed by Mr McMaster amounted to only £16,000.
He has had to take on more loans to try to get the conversion finished and said he was now living month-to-month trying to pay them off.
When BBC Scotland News visited the home, the conversion was still an unfinished construction site.
Despite attempts to get £15,000 back from Mr McMaster, Mr Jardine has had no luck.
Chris Jardine is one of seven homeowners who shared documents with the BBC Scotland News. They include bank statements, contracts and estimates, and WhatsApp messages with Mr McMaster's companies.
They claim they paid thousands of pounds to Mr McMaster to carry out extensions, renovations and conversions which remain incomplete.
Together they paid at least £220,000 to Mr McMaster and his companies, but the work is still largely unfinished. They believe they are tens of thousands of pounds out of pocket.
Grant Kilpatrick, 53, said he hired VJL Builders in July 2022.
"Initially he seemed quite plausible and things did seem to be moving," he said.
Mr Kilpatrick and his wife Lynsey both work as paramedics. In early 2022, Ms Kilpatrick had a stroke and they decided they would use the insurance money to renovate their house.
"When she had that we thought: 'Why put things off, you don't know what's round the corner with your health' - so we decided to go ahead with it," he said.
They hired VJL Builders to do the work, a contract worth £68,000 to build an extension and convert an outhouse into a garage.
It was supposed to be a 12-week build, but the work was never finished.
He said he paid Mr McMaster's firm £58,000 before contact stopped. He estimated the value of the work carried out was about £38,000.
Mr Kilpatrick reported the matter to Police Scotland but was told it was a "civil matter".
"I think he should be prosecuted. He's stealing people's money, he's causing misery for people, he's putting people in financial hardship, emotional hardship - it puts a big strain on people," he said.
"If I stole £20,000 from an individual or a company then I would be prosecuted. He should not be allowed to own a business where he can do this again.
"There should be some kind of law that protects us, that protects consumers from people like him."
Police Scotland said it received a report of alleged fraud on 9 June last year.
A spokesman said: "Inquiries were carried out and suitable advice was provided."
Lawrence Keenan, a retired automation technician, paid the builder £53,000 for a full house renovation, which was never finished. It had to be re-done after the work that was completed did not meet building control standards.
He went to trading standards, who told him to confront Mr McMaster.
Mr Keenan did this, but was unable to get his money back so considered legal action.
Despite not having an official contract drawn up with Mr McMaster, he said his solicitor said the texts and messages they exchanged would be enough for him to have a case.
However, he advised Mr Keenan that it would likely take years and even if he won he would likely never see any money.
"He'd very likely just shut his business up, go bankrupt and open again as another name and I wouldn't get any money," Mr Keenan said.
"And I would be stuck with the £20,000 lawyer's fee, so he said it probably wouldn't be worth doing it."
Data from Advice Direct Scotland appears to show there has been a rise in building work scams following the Covid-19 pandemic.
The consumer advice service's online scam reporting tool has seen a 42% increase in building work consumer cases across Scotland over the last year, while building work scams increased by 31%.
North Ayrshire Trading Standards confirmed that it had received seven complaints against VJL Builders and Russell McMaster.
Meanwhile, Mr McMaster has run a string of business listed on Companies House under different variations of his name. Most have them have been dissolved.
The Daily Record also reported dealings of his previous businesses leaving customers in debt after closing down in 2006 and 2013.
VJL Builders was registered in August 2022 - a month after he started working for the Jardines and Kilpatricks - but was dissolved on 30 January.
His other business, Alex McMaster Builders, was registered in February 2021 but is expected to be dissolved in March.
BBC Scotland News contacted Mr McMaster on four separate occasion by post and email in November last year. He did not respond to allegations laid out by his clients.
The BBC also approached his home address, where both businesses are registered, but there was no response.
Mr McMaster later responded via text message, saying: "I am unavailable for comment on this matter."