The Consumers' Association (CA) is calling on victims of the endowment policy misselling controversy to seek compensation.

It follows warnings from insurance companies that up to 80 per cent of home owners with endowments may be unable to pay off their mortgage because 6.2 million policies are in trouble.

Only 200,000 of an estimated five million home buyers with failing endowments have claimed so far.

The CA campaign includes a web site, www.endowmentaction.co.uk, with a letter generator to process an official complaint when applicants fill in basic details and tick the necessary boxes.

CA director Sheila McKechnie said: "Endowment misselling is nothing short of a national scandal that has shaken the lives of millions of people.

"People were given bad advice. They were given guarantees about how much they would raise and they were not told there was a risk."

If all those advised to pick a fight actually do so, they should receive an average £3,000 per household, says the CA, blowing another £15 billion hole in the balance sheets of leading insurers.

If the stock market keeps falling, the bill could go even higher than the £11 billion compensation bill arising from pensions misselling.

But the Financial Services Authority has refused the inquiry into endowments, which it granted on pensions.

Nobody denies many endowment salesmen were guilty of persuading home buyers to tear up one policy and take another to boost commission payments when the property market boomed in the late Eighties.

But it could be extraordinarily difficult to unravel the compensation claims and there is scepticism from analysts about the supposed horrors of the great "endowment scam".

Home buyers facing the biggest shortfalls will tend to be those who borrowed most to buy in the expensive areas of the South-East.

Many will be sitting on huge tax-free capital gains on their homes, far greater than they could possibly have imagined when they moved in.

Ray Boulger, senior technical manager at mortgage brokers Charcol, said:

"Clearly, some people with endowment mortgages received bad advice and have been disadvantaged. But the true figure is nothing like as high as the CA suggests.

"In the late Eighties, when interest rates were high, many people opted for low-cost endowment loans because they were cheaper.

"Clearly, if they were told that an endowment was guaranteed to pay off their loan, that was untrue and they were missold.

"If they were simply told a surplus was likely, that is not a missale. Our policy at that time was to tell people endowments weren't guaranteed to pay off the loan so I do not think we are at risk."

The other weakness in the CA's position is its failure to acknowledge the benefits we enjoy from the lowest interest rates in 40 years.

Mr Boulger said: "One reason why endowments struggle is that we are in a low inflation, low interest rate age, impossible to imagine ten years ago.

"Do people want a 13 per cent mortgage rate and a lump sum on their endowment at maturity or do they prefer a four per cent mortgage rate with risks of an endowment shortfall? See both sides of the equation before you decide you have been badly treated."

If you believe you have a case for a claim, like a letter from a financial adviser guaranteeing your loan would be covered, visit the CA web site or send an A4-sized stamped addressed envelope to Department Z, Castlemead, Gascoyne Way, Hertford, SG14 1LH.

Mr Boulger also advises guarding against the worst by overpaying into your mortgage.

Usually you can pay up to ten per cent per year extra into your mortgage, without incurring early redemption penalties.