Britain’s financial regulator, the Financial Services Authority (FSA), will make insurers and other financial companies alert customers when their right to complain about improper selling of mortgage endowments is due to lapse.

The authority has ruled companies must warn customers who face a shortfall from their mortgage endowments at least six months before their right to complain ends. The rule is effective from today.

Mortgage endowments are used to pay off a home loan by investing in financial markets. They were sold commonly in the 1980s and 1990s by life insurers and banks, but stock market falls have left customers with an estimated $72 billion shortfall in the money needed to repay loans.

Consumer groups have said many customers were not told about the risk of a shortfall. Endowment holders have the right to complain for three years after they are warned that the investment is unlikely to repay the loan.

“We are applying these measures straight away to ensure consumers who believe they were mis-sold their endowment policies are clear about the date their right to complain runs out,” FSA Retail Themes Director Anna Bradley said.

The FSA says the total number of complaints at the end of March about endowment mis-selling was 452,201. Affected companies have paid or set aside about $2.5 billion to compensate customers.