Hi BH Hell,
I'm in the same position as you - practically in tears today with exhaustion and stress.
You should probably go to those neighbours during the day and explain that you can hear everything. If they still ingore your request and play music loudly at unsociable hours, then contact your landlord to contact their landlord (if they are renting).
In my case I've asked my neighbours many time to tone it down, but it made no difference (there are 8 of them living in a one-bed apartment, so you can imagine the noise).
So this morning, I'm writing a letter documenting the noise, the time it starts at, duration, loudness, affects on me etc. I'm going to follow it up through my landlady and the president of our building.
I hope your situation gets resolved, because it is such a huge cause of stress.
Ragazza