Many of those who will be affected by a change in the way homeowners on benefits are supported are yet to be contacted about the change, it has emerged.
A total of 124,000 households, including 57,000 pensioners, will be affected by the end of a mortgage payment lifeline in April, according to Royal London.
Support for Mortgage Interest (SMI) gives help to those who are in receipt of certain income-related benefits such as Jobseekers Allowance and Pensions Credit.
It covers the interest payments on mortgages and some home improvement loans.
However, in April those who have the payment will be switched onto loans, which will need to be repaid to the government with interest when the property is sold, transferred into new ownership or on the death of the recipient (or their partner).
A Freedom of Information request (FOI) by Royal London revealed that not all of those in receipt of the payment have been contacted about the change, and just 6,850 households had signed up for the new loan scheme.
Those who do not agree to move over to the loan scheme will have their mortgage help terminated in April.
Helen Morrissey, personal finance specialist at Royal London, said it was truly shocking that so many thousands of low income families had not received information about the change.
She said: "If thousands of people fail to complete the process in time they could face real hardship and even potential repossession if they can no longer afford to meet their mortgage interest bills.
"The Department for Work & Pensions should pause the implementation of this policy until it is confident that everyone has had full information about the changes and the time and support to make an informed decision."
A Department for Work & Pensions spokesman said that the change to Support for Mortgage Interest would save the nation's taxpayers £160m a year.
The spokesman said: "Support for Mortgage Interest is being reformed so a safety net is in place to protect homeowners from repossession when they need it – and to make it fair to the taxpayer who funds it.
"We are contacting all SMI claimants to explain the change and to signpost them to independent advice.
"This change provides a safety net to help people stay in their homes and avoid repossession.
"Over time, someone's house is likely to increase in value, so it is reasonable that anyone who has received financial help towards their mortgage should be asked to pay that back if there is available equity when the property is sold."
The loan that replaces Support for Mortgage Interest is only repayable after the property is sold providing there is enough equity after the mortgage is paid off.
If there are insufficient funds after the mortgage is paid off, the loan is written off.
The DWP spokesman said all Support for Mortgage Interest claimants will be written to and also contacted by telephone.