If you have buildings insurance most cover free legal advice, I would check with your insurer. I know how you feel we have just gone through the same situation, broken Ariel, damage to our drain cover and inner pot, render knocked off our garage. I complained to the builder and asked when it’s going to be put right, his reply “ain’t going to happen”, he’s now left the sight. They are now having problems with French doors and want my husband to fix them, it’s his line of work. He’s told them to get the builder out. They’ve built a raised decking 1.5 meters bigger than allowed, moved the access to it, and are refusing to put up privacy screens on both sides. They have a we can do what we want attitude. However, someone has reported the raised decking to the council so I expect something will get done about it.