Right MSG, let’s get down to the nitty gritty!
Is the guy a big hardy looking bastard? What language do they speak? A nice note through the door , explaining you are going off your nut , and if it doesn’t stop, you will make moves to make it all official.
Fight fire with fire , get your tunes on . Then if you both want rid of each other , you could say “ I have viewings between 6 and 8, if you want rid of me , keep the noise down or even better,, go out”
The council quite simply can’t ignore unregistered landlords, and if they do , I would bring it up with your MP/MSP . You may find your MSP is keen to impress just now!
Tell your doctor you can’t sleep, you are massively depressed, you are going into a dark place. Lay it on thick( not that you need to!). When they are making a racket, phone 999 , tell them you think some domestic violence is going on.
You don’t want to become obsessed with it ( maybe to late) but it’s not going away on its own. It’s time to get nasty, while of course , keeping yourself on the right side of the law.
The authorities , can’t and won’t ignore you if keep at them.