Debt on Our Doorstep, a campaign network originally started by Church Action on Poverty, organised a demonstration to coincide with the opening of a new BrightHouse store in London.
Campaigners say that BrightHouse, formerly called Crazy Georges, charge inflated prices for household appliances to people who have difficulty getting credit.
The Sunday Mirror reported a washer-dryer available for £385 being marked up to £527 and then when the interest and 'optional' service cover is added it totals £1168.
The Brighthouse stores are owned by Hands' venture capital fund Terra Firma.
Brighthouse offers credit to people with chequered credit histories and its stores are located in deprived areas. While its credit terms are transparent, campaigners argue that the firm charges high prices for goods, that its repayment methods don't allow for quick clearing of the debt and that its optional service cover (OSC) is ruinous for the poor.
A Whirlpool 1200rpm washer dryer, advertised on the net by Brighthouse for £491.98, can be bought on the high street for £350. But using the Brighthouse 156-week repayment method, together with OSC, brings the total price to £1,094.
Faisel Rahman, of Debt On Our Doorstep, said: "Why should poor people have to pay so much for basic things?"
But a spokesman for Brighthouse, which has more than 130 outlets across the country, said the firm allowed people who would otherwise go without to buy goods, and that people who took out service cover had peace of mind that parts would be replaced for free.
Brighthouse used to be known as Crazy George's. It was driven out of the French market nine years ago for charging high interest rates.
Brighthouse is the trading name of Caversham Finance Limited, which, as a subsidiary of Thorn Group, was taken private in September 1998 in a deal arranged by the Principal Finance Group of Nomura (now reconstructed as Terra Firma Capital Partners).
In a separate development BrightHouse have backed down in a Manchester court case that DOOD have been involved in.
Originally established as a campaign group by the Money Advice Association and Church Action on Poverty, Debt on our Doorstep is a network of support that has grown to include the Local Government Association, Unison, Oxfam, the New Economics Foundation, the Association of British Credit Unions, and a huge number of local advice agencies, credit unions and church and community organisations, as well as thousands of individual supporters.