They moved in around 3 years ago with their toddler, back then he screamed all day every day. Never ending tantrums. When they put him to bed at 6pm he would scream and yell for up to 2 hrs before finally exhausting himself, but often some time after midnight he would wake up again and start yelling and screaming.
For the first year this happened every single day, and I'm not exaggerating. We called over at one point (with wine and a smile I might add!) to talk to them about it and see if there was a solution we could work out. They were immediately defensive and sent us away saying that this is what kids do and refused to entertain any suggestions of moving him to a different part of the house or attempting to soundproof his room.
Over the years he does it less frequently (around 1/2 times a week) but now he is bigger he is even louder. I hear it through earplugs. It's audible in other rooms of the house and not just the one immediately adjacent to his.
I'm at my wits end. I opened my window one night and yelled at him to 'shut up' as he'd been screaming for 20 mins at 2am and the parents were upstairs in their loft conversion apparently oblivious.
WTF do I do? This is getting past the point of acceptable and has been going on for so long now that I doubt he'll ever grow out of it. Can any parents with experience of kids like this help me with how to approach them? We're a bunch of late 20's/early 30s professionals who have 1 party a year and are early to bed. We cause zero disturbance to any of our neighbours.
Any and all help appreciated, thanks from a desperate bunch of tired people.