You won't get much sympathy for this, it's MUMSnet... but I agree with you, & YANBU, my neighbours kids are never off theirs, the screaming & shrieking is off the scale, it starts at 3:30 when they come home & carries on until almost midnight some nights, and it's all weekend.... (these kids are 3,5 & 6) my other's neighbours daughter is kept aware by the noise & that neighbour has spoken to them..... nothing has changed.... and nothing will
But try even raising it as an issue with the authorities, nobody will do anything....we're just supposed to suck it up (although I defy my local EHO to put up with noise I have to put up with & keep smiling) - but didn't you know, children are above reproach in 2019, they can do exactly as they please, they have more "rights" than adults, & woe betide you even have an opinion on this, still less express it...
I'm really sorry for you, but would suggest you get some really good noise cancelling headphones & consider moving if/when you can (I'm selling my house & moving because of this).
Neighbour noise is a huge issue and increasing year on year, it has a massive effect on people's mental & physical health, but until such time as neighbourly consideration is restored (unlikely) or politicians actually recognise the problem & bring in enforceable noise control legislation, there really is nothing you can do.