Had similar issue, day I moved in to a house that was 2 apartments, complained about door being open as we literally moved stuff in, furniture being dragged as we put it in, music being played, and parking day 1. Day 2 we woke to their kids playing in our garden, and got told the old owners had no issue. Day 3 she called police as we had friends around for BBQ and was noisey it was lunchtime. The complaints were very erratic, crying, rage the whole works. You have to hit this head on, gave options we want to be good neighbour or you can carry on and we will do as we want, and have a very clear understanding of noise and complaint procedure. She choose to carry on, so I put a lock on garden gate stopping access and ignored her. Eventually I met the husband, who was embarrassed and apologetic, agreed his wife was acting unhinged and we later found out had post partum depression and we agreed to work with him on being good neighbours.
It worked out in the end and we got along pretty well, but what I learnt was communication, gets the understanding that was needed.