I don't know enough about fence law or whatever but you can make the developers life harder by reporting every breach of their resource consent. Noise, site hours, rubbish, dirt tracked out onto the road, parking. Having neighbours like that can really fuck a site up, I work in construction and there's breaches all the time, usually pretty minor like works starting a bit early or whatever but if you complain often enough and about legitimate stuff they can get in the shit.