Out of the cold

My Nan is 77 years old. Three years ago she had free loft insulation installed. The man who installed it was very rude and while he was in the loft he put a hole in the heating flue. we have no way of proving it was him but no one else had been up there. luckily my Nan is cautious of gas and had her heating checked over every year before she started using it in the winter. When she had it checked a few months after the insulation was put in, the hole was found and the engineer had to lock off the heating system because if it was used the house would fill with carbon monoxide. She has spent the last three winters using a calor gas heater, upstairs is freezing as the windows are single glazed  and she still has to ware a coat downstairs. We have been told a completely new heating system needs to be installed because of the age of the old one which will cost a minimum of £3000. she earns £20 a year to much to get any help from the government or charities.  We help as much as we can but we are struggling ourselves. Being able to heat her home would improve my Nan's quality of life 100 times. please help with even the smallest amount.