Been there and done that barneymc!!!
Took us a year of going to court to get the house in the first place builders tried to re-sell the house because we refused to sign off on the snag list, and then tried to add 100k onto the price. Looking back we should of just let the house go, but we were young and not as wise as we are now, and we just wanted our house that we had worked and saved for. The only reason the builder are even talking to us about the insulation is because we are not the only ones having this problem. If it was just us they would of just laughed in our face and done nothing about it. I'll be godsmacked if they ever do get it fixed, the whole estate set up a commitee against the builders because so many people had major problems with their houses. That i know of no one has had anything fixed, they've just paid to get it fixed themselves. Apart from a friend of mine that cant fix her problem cause the road is in the way. She can drive her car into the driveway no problem........it's geting out of the car she cant do. In order for her to use her drive way she would have to climb in and out of the car via the boot or the sunroof!!!! It sounds unbelievable i know but all 100% true!!!