About 14,500 people who have fallen victim to illegal money lenders have been helped by a specialist Birmingham team, it has been revealed.
The Illegal Money Lending Team, run by Birmingham City Council, was set up in 2004 and gives advice and assistance to those affected by loan sharks.
More than 310,000 UK households are using illegal money lenders, latest figures from the government show.
Investigators revealed loan sharks have charged interest rates up to 130,000%.
The Birmingham unit now covers the North West, Yorkshire and Humberside, South East and Central England, helping people to escape the clutches of loan sharks.
In the past six years, investigators across the UK have secured convictions which have led to jail terms totalling 80 years.
'Bullying and power'
A total of £25m in illegal debt has been written off, and £2.5m has been seized and confiscated from loan sharks.
A spokeswoman for the Birmingham team said many of those convicted were also found guilty of related offences including blackmail and threatening behaviour.
The team has released telephone answerphone messages that loan shark victims have received to highlight the danger of taking out a loan with an illegal money lender.
One of the messages said: "You think for one minute you're not going to pay me another penny?
"You better think again mate because I will take your head off. Believe it or believe it not. And let's hope I get you up the factory today.
"You little robbing, lying, toe rag. I'll kill you."
Tony Quigley, who manages the team, said: "Illegal money lenders think they are a community service, but it destroys harmony. It's based on bullying and power.
"We've got operations going on all the time… we intend to bring as many as possible to book to tackle this despicable crime."
'Somewhere to turn'
One victim of a convicted loan shark, who asked not to be named, said she took out a loan for £150, but ended up paying back £5,000 over five years.
"I didn't know which way to turn. I'm not gullible or stupid but when you've got a person like him, you get the threatening letters, you just pay it because you didn't want him coming to your house," she said.
She received support from the Illegal Money Lending Team, and the loan shark who targeted her was jailed earlier this year for four years.
"When they got involved it was unbelievable. There's probably a lot of people out there going through what I went through and they have got somewhere to turn," she said.
BBC Inside Out West Midlands, at 1930 GMT on Monday 22 November on BBC1.