Craig Jamieson began reporting his suspicions about his carbon credit investments last April.
A company called Eco Business Management (EBM) contacted Mr Jamieson in January 2013 having already recruited a flatmate as a customer.
The Edinburgh-based investor says: "I was offered carbon credit shares in Caprock WindRanch. I was told that these carbon credits were of UN standard and they would be purchased from a company called Eco Asian Consultancy, which was regulated by official bodies in Singapore, and that my investment was protected by such bodies."
EBM told Mr Jamieson that a 20% return on his investment was realistic over two years.
"I also was given written assurances that if I wished to terminate any investment vehicles, this would be done without any problem, with my initial investment, or a sum just below, being paid back.
"I also received statements from Eco Business confirming increased values in my carbon credit investments."
The credits, permissions for companies to burn carbon, are traded by large established brokers, but the former Financial Services Authority issued its first consumer alert on dubious schemes in August 2011.
The watchdog warned that the market was unregulated with no checks on the quality or validity of credits, which might be overpriced and virtually unsellable.
EBM's sales pitch however was so effective that Mr Jamieson was persuaded to make two further investments over the next month, into carbon credits for Konaseema Gas Power and Salto Pilao Hydro Power - which like Caprock were credible energy installations that could be checked out online. Mr Jamieson's total outlay had now reached £20,000, in what he believed were "ethical" investments with green credentials.
Then the broker who had contacted him, a David White, offered Mr Jamieson a fourth opportunity, carbon credit investments in an Indonesian venture by MedcoEnergy, for what was said to be an instant 30% profit.
"But the advisory letter this time included a warning against "disclosure to anyone of the details of the transaction".
This time, Mr Jamieson's suspicions were aroused and he reported EBM to the Financial Conduct Authority and Action Fraud on April 8.
Ironically, six days earlier, the FCA had issued an alert about a new blacklisted company that was targeting UK investors - Eco Asian Consultancy. Mr Jamieson tried to contact EBM to sell his investments.
He recalls: "Firstly I was told it was not possible to do this at this time. David White had turned my dealing with Eco Business Management over to another broker called Philip Clarke, as he was 'going away' for a few weeks to work on other projects. Philip Clarke informed me that the shares would be sold 'soon'. They weren't.
"After that, the company website was taken down and emails sent to the Eco Business Management address were returned.
"I then tried to contact Eco Asian Consultancy. The phone contact did not work and emails to their address come back as unrecognised."
Finally, Mr Jamieson contacted SJL Risk, the Essex-based company to which his second and third payments had been made. He was told SJL had "never heard of" EBM, and that the broker for his second and third investments was Abacus Advisory - a company Mr Jamieson had never heard of.
According to Companies House records, EBM applied for voluntary liquidation last November, its director Sean Madden having no other past or present listed directorships. It was not possible to contact him or Mr White.
Abacus Advisory was set up in September 2012 with one director, Philip Clarke, and £1 of share capital.
Its website says the firm is "an independent, highly experienced specialist firm of professionals operating in the alternative investment sector".
It is said to be located in the City of London, it is "well-placed to draw on a wealth of expertise both in-house, locally and internationally", while its "senior executives have many years of successful experience performing a variety of roles within various financial companies" and its "research team comprises many experts with local-based knowledge on an international scale".
The website also warns that the company is "not authorised or regulated by the Financial Conduct Authority".
The Herald received no reply to calls and a message to the Abacus website .
Harvey Bennett, a consultant for SJL Risk, said the company carried out trade execution in the carbon credit market and held clients' investments securely, but did "not set pricing or give advice".
Mr Bennett said: "A few clients have phoned up who can't get hold of Abacus. We would never transfer clients' holdings without written authorisation from a broker."
He said SJL was not regulated as carbon credits was an unregulated market.
Mr Jamieson said: "This is a scheme running into the millions, which has had a disastrous impact on so many people trying to make ethical investments."
He said despite the embarrassment of becoming a victim, he is continuing to report and highlight his experience "to stop it happening to other people".