Hey madmondeo. Sounds like a nightmare! You say the owners are unapproachable: have they actually been approached? If so, what happened? It seems to be a noise and potential welfare issue (can you tell if they have food, water, shelter? If so, the RSPCA will do jack all to help). If the owners are aware of this and are making no moves to work on it, then get in touch with your local Council's Environmental Health dept. and urge your other fed up neighbours to do the same. You'll be asked to fill in a noise diary for (I think) about 2-4 weeks.
P'raps other ABers can give a bit more advice.
Good luck, keep us updated! Lisa x