The Dorset-based firms were Bankruptcy Limited, Intl Marketing Limited, UK Bankruptcy Limited and Mortgage Link Limited.
They sent mailings that claimed recipients could have been mis-sold an individual voluntary arrangement (IVA), suggesting bankruptcy may be a better option.
People accepting the advertised solution would have had to pay additional fees to switch debt solution and this may not have been in their best interest.
The poor quality advice and misleading letters breached the OFT’s debt management guidance.
David Fisher, director of the OFT’s consumer credit group, said: “Companies must not use misleading mailings or give advice that they know may not be in the best interests of borrowers.”
He added: “Where the OFT has evidence that companies have breached its guidance, it will use its powers to stop them from doing so again.”
The four companies were linked to each other in various ways, including through common directors. They were also tied to potentially misleading trading names such as The IVA Council and IVA Watchdog.
The OFT also refused to grant licences to two other associated businesses called Petitions Direct Limited and UK Restart Limited.