Debt on our Doorstep has launched an "anti-shark" campaign to combat usurious lending to the poor.
The group, whose members include Barnardo's, Help the Aged and the Methodist Church, is to protest outside the premises of hire-purchase company Brighthouse one day a month for the next year.
But spokesman Faisel Rahman said demonstrators may eventually target pawnshops and high-street moneylenders too. "It will be direct action on a mass scale," he said. "If it works, we'll do it for everyone."
The first protest was held last week outside a Brighthouse store in north London. The firm, which has been banned from France for charging high interest rates, has about 130 branches in the UK.
According to Debt on our Doorstep, whereas a washer-dryer from Currys costs £300, purchasing one from Brighthouse through its 156-week repayment plan, would cost £1,170.
The company is owned by venture capitalist outfit Terra Firma. "Venture capitalists are profiteering from poor people," said Rahman. "Why should poor people pay so much for basic things?"
The campaign has asked for support from former French Prime Minister Lionel Jospin, who helped to force Brighthouse, then known as Crazy George's, to stop operating in France.
Brighthouse declined to comment.