By Paul Lewis
BBC Radio 4's Money Box
A meeting of people who have shared appreciation mortgages
Thousands of people who say they are trapped in their home by mortgages they took out in the 1990s could get the contracts changed by the courts.
Lawyers say these deals were unfair giving too much to the banks and too little to the borrowers.
Victims are being asked for £5,000 each to fund a multimillion pound test case.
But some are concerned about how they have been asked for the money which they may lose.
The deals, called shared appreciation mortgages or SAMs, were a form of equity release and offered by Bank of Scotland from 1996-1998 and Barclays in 1998.
The banks lent customers a quarter of the value of their home at no or low interest. In exchange, the banks received the loan plus three quarters of the growth in the price of the home when it was sold.
With house prices trebling since then the banks now own more than half the value of most of the properties mortgaged. That means the owners cannot afford to buy anywhere else if they sell.
Previous attempts to take court action have failed. But a new consumer credit law which came into force in April this year could now be used to challenge the deals in the courts.
Hilary Messer, Director of solicitors Richard Wilson Pangbourne, told Money Box on Radio 4
"If the courts take the view, and we think they will, that the relationship between the homeowner and the bank is unfair that opens the door for the contracts to be revisited and for the court to substitute what they believe is a fairer outcome."
Ms Messer says the case will cost many millions of pounds. And the SAMs pressure group Struggle Against Financial Exploitation (SAFE) is asking its 1,500 members to stump up £5,000 each to fund it. Some people were not happy with the letter it sent.
One listener, Dawn, whose parents have a SAM, told Money Box
"I wasn't very happy with the tone of the letter. It was tugging at the heart strings of the couple with the SAMs or the family. Do we get twelve months down the line and have to hand over more money?"
But Elaine Williams of SAFE defends the way the letter was written.
"We had to be upfront with people. I have had people say I have sold a ring and the cheques in the post. We have always worked to help SAM holders and now we have the best chance in history of doing this."
There are about 8,500 people with SAMs which they have not redeemed who can join in the action. The £5,000 will almost certainly be lost unless the case is won, which is by no means certain. Cases will run into a time-bar 12 years after they were taken out. So some of the early contracts could run out of time by the end of this year. The case could take two years or more to resolve.
BBC Radio 4's Money Box was broadcast on Saturday, 27 September 2008 at 1204 BST.