About four years ago both our neighbours and ourselves had a single storey extension built to make our kitchens larger and provide a utility room / bigger hallway. We now have a leak from the water main which, instead of being re-routed outside the line of the extension, was in fact left in it’s original place and buried in the concrete slab under the new kitchen. The solution to this is to run a new supply to our house (and the neighbour, as when our old main is interrupted they will lose their water). The cost of this work is about £1600. Our insurance company (M&S) is not interested as there is no damage to repair, just a leak that they determine is a maintenance issue. Are we able to pursue the builders who did the work originally, or do we have some grounds for complaint or compensation with Building Control (as I understand it the main should not have been signed off by them) ?