The Halifax is so cash-rich that it has plans to hand out pounds 3bn to members when it turns itself into a bank this summer. But it is pursuing an aggressive "old debt for new" policy against individuals whose negative equity liability it bought from the French bank BNP in 1995.
Overnight, 22,000 BNP mortgage holders found their home loans transferred to the expanding building society.
For some people the purchase means that negative equity has returned to haunt them, long after they left their homes.
Divorcee Louise Marks is one BNP borrower stalked by the Halifax's detectives, despite losing her home.
"Just before last Christmas the Halifax sent me notice of bankruptcy claiming that I was jointly responsible with my ex-husband for a debt of pounds 81,000," said Mrs Marks, who has three children.
In 1989 her husband took a pounds 150,000 BNP mortgage to buy a pounds 210,00 new home in Bishop's Stortford, Herts. Two years later her husband was made redundant. The prevailing interest rate at that time meant their mortgage repayments came to more than pounds 2,000 per month.
"We struggled on for as long as we could and lived on our savings. We did not run up any arrears but it became obvious that we could no longer afford to live in the house," she said.
"We discussed the whole matter with BNP and rather than run up debts or have the property repossessed, we posted the keys back to the lenders, moved into a rented house and never heard another thing from them."
Later Mrs Marks learnt that BNP sold the property for pounds 130,000. As well as losing more than pounds 50,000 in equity invested in the house Mrs Marks has calculated that they had paid pounds 75,000 in interest repayments by the time they moved out.
Mrs Marks, who had to live in a hostel for the homeless, took her case against the Halifax to the Mortgage Ombudsman.
"He told me that the Halifax were acting within the law but I want to say to them: 'Don't you think I've been through enough?' Their solicitors pester me every week at work; I have explained that I earn just enough to keep myself and the children in a Housing Association rented property and no more."
The Halifax confirmed it is pressing claims against debtors with old BNP mortgages.Reuse content