Thousands of people are being ripped off by companies providing unregulated services such as will writing, claims the first Legal Ombudsman.
In his first report, Chief Ombudsman for England and Wales Adam Sampson said the most complaints he saw concerned conveyancing, family law and wills.
He called for action to be taken to ensure consumers were not left vulnerable by unregulated services.
Only a tiny fraction of legal services must be provided by a qualified lawyer.
Many others including will writing, divorce and employment can be done by unqualified and unregulated individuals and organisations.
"One service which crops up a lot is will writing. It's a service carried out often by will-writing firms who aren't regulated," said Mr Sampson.
"Because of this, customers are left with little means of redress when things go wrong.
"We've seen similar confusion about claims management companies, with lots of consumers believing they're getting a legal service even though most of the work is carried out by a non-authorised person. Again, we can't help."
The legal ombudsman was appointed in October 2010 and can only act on complaints from those using the services of qualified lawyers.
Consumer organisation Which? and the Law Society have backed the ombudsman and called for more protection for customers.
They said bundling legal services with financial services, including those offered via the internet, had posed serious dangers for consumer protection.
Which? executive director Richard Lloyd said: "As the legal-services market continues to grow in both size and complexity, it's crucial that consumers who have paid for a legal service that's not up to scratch know where to turn to get help.
"We want the government and regulators to wake up to the current lack of clarity and to provide a clear and straightforward route of redress for consumers.
"The arrival of a legal-services market in which consumers will, potentially, have complaints about hybrid services poses some serious questions about who they'll be able to turn to for help."
Des Hudson, chief executive of the Law Society for England and Wales, said: "The gap in regulation which allows unregulated cowboys to operate in areas like will writing does not just cause unfair competition to solicitors, who provide a regulated, professional service.
"It is also damaging to consumers because the unregulated providers are not insured, do not provide a compensation fund and are not covered by the Legal Ombudsman's scheme for consumer redress."
A spokeswoman for the Ministry of Justice said will writing was an important issue and that it welcomed the report.
She added the department will await the outcome of the Legal Service Board's ongoing work.
- An earlier version of this report included a reference to immigration services being provided by unqualified and unregulated individuals and organisations. In fact, these services are regulated by the Office of the Immigration Services Commissioner or other professional bodies, including the Bar Council.