Builders 'magically' appeared today to fix a roof which had been leaking for nine months, hours after the latest Wimbledon Guardian news story on repairs and maintenance issues involving Circle Housing tenants.

Under-fire Circle Housing take family 'plagued by leaky roof for nine months' to court after they refuse to pay service charges

It was the latest in a series of articles exposing the terrible record of repairs plaguing residents and probing why and how the problems had been allowed to happen.

Our series of investigation pieces into builders overcharging for repairs eventually led to a £170,000 refund to housing association tenants.

Desperate residents began contacting the newspaper in January 2014 complaining about living for months with leaking roofs, pot-holed paths and crumbling walls.

After reporting their complaints, a whistleblower and former employee of Circle Housing Merton Priory (CHMP) contacted the paper backing up claims of contractors not turning up to appointments, overcharging for work, or charging for uncompleted work.

The newspaper reported the claims along with detailed evidence from residents, sparking calls from local councillors for an independent audit into CHMP's repairs and maintenance service.

CHMP manages more than 9,500 homes across the London borough of Merton. Most repairs and maintenance work for these homes are carried out by Keepmoat Property Services, which has a £220m five-year contract with Circle Housing.

After the initial audit in September 2014 uncovered serious overcharging, the director of property services left the company and Keepmoat let go a number of sub-contractors.

A wider investigation was then commissioned from Savills which found Keepmoat had overcharged by £170,000. Keepmoat then repaid the money to CHMP’s repairs and maintenance service.

The results of the investigations were only published in August 2015, after sustained pressure from the newspaper.

Since the investigation, the newspaper has continued to hold CHMP to account over its repairs and maintenance service - and has questioned findings that no leaseholders were overcharged by builders, as they share blocks and bills with tenants.

The newspaper has been responsible for significant improvements to the repairs service, where MPs and councillors, some of whom sit on CHMP’s board, failed to act.

The investigation has also been a victory for taxpayers in Merton, who indirectly fund repairs and maintenance to housing association tenants’ homes through housing benefit.