The national charity has lodged a super complaint with the Office of Fair Trading (OFT) and is calling for a ban on cold calls offering credit or debt management services, and a ban on up-front fees.
Citizens Advice research found that debt management firms made 840 million cold calls in 2009, with loan fee scams affecting at least 110,000 people a year, costing the UK public £190m a year.
In its report, it warned that victims of the recession had been being targeted by firms who phone or text out of the blue offering to help them find a loan.
Customers are then charged a hefty fee for a loan that often fails to materialise, and are unable to get their money back, Citizens Advice said.
It found that in many cases consumers are persuaded to part with bank account details and have money withdrawn from their account without their consent.
Citizens Advice said that firms appear to target people unable to access mainstream credit because of a poor credit history, low income or current financial difficulties.
Gillian Guy, chief executive of Citizens Advice in England & Wales, said: “Our evidence suggests that rogue operators are cashing in on the desperation of people hit hard by the recession who are least able to afford it, and that this problem is set to grow much worse.
“The framework of consumer protection about unsolicited marketing and up-front fees charged by credit brokers are not only complex, but loopholes give too much room for bad practice to flourish.”
He added: “Because of the seriousness of the situation, we are making a super complaint to the OFT and asking them to launch an immediate investigation with a view to deciding that a ban on cold calls and upfront fees is appropriate.”
