The company hired by Durham County Council to do the work on Mrs Chappell’s house, Tolent, went bust before the installations were completed.

Tolent sub-contracted the work to another firm, Westdale North Ltd, which says it is “still on site, and working on issues that have arisen.”

It added that it was doing the work “as a goodwill gesture although it may not legally be required to do so” adding “the care and consideration we have for residents is a core part of our service.”

The company said the work had been signed off by the Council and Tolent before it went bust, adding: “Some issues that were raised with Tolent were not communicated to us, due to them no longer being in business.”

Durham County Council’s head of planning and housing, Michael Kelleher said it had been “a complex situation, with the collapse of Tolent causing delays outside of our control and we understand residents’ frustrations.”

Mr Kelleher said the council has set up an email address for concerned residents, arranged for inspections to take place at affected properties and provided Westdale North with a list of issues raised by residents.

“Westdale North has carried out extensive work to resolve the issues and we will continue to liaise with them to ensure any outstanding problems are rectified,” he added.

DSENZ said it was planning to overhaul the current system.

“The government has inherited a situation where there are several organisations with different roles and responsibilities, producing a fragmented and confusing system of protections for people wanting to make their homes more energy efficient,” it added.