A husband and wife say they do not know how they will heat their home due to damage which happened after insulating their house almost 20 years ago.
Alwyn and Delyth Williams, from Penisa'r Waun, Gwynedd, were part of a government-backed scheme in 2004 for cavity wall insulation.
But they have since had damp issues and said work by guarantor company CIGA to help has only worsened the situation.
CIGA said it had gone beyond the guarantee agreement to help the couple.
It added it had managed the case effectively and blamed poorly sealed windows and maintenance for issues at the couple's home.
Hywel Williams, MP for Arfon, has campaigned for the UK government to address people's concerns about the scheme for years, and has called for the homes to be retrofitted.
"Some of my constituents are still living with the consequences of this botched scheme; damp homes, mould, flaking render and condensation," he said.
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Living with damps, cracks and mould
For Alwyn, 79, and Delyth, 73, the situation is becoming more and more difficult, with cracked walls, bubbled paint and plaster falling off the walls.
Ms Williams said: "When it rains and blows, water pours in through the window. It's just getting worse every time someone comes here.