I also hv a my neighbour from Hell upstairs.
Few months ago, this very violent old man keeps banging on my door loudly till my door shakes n even peep on the peephole.
Later heard his wife scolding him that it was their upstairs neighbour who complained abt them slamming their door n gate louding practically daily at 8+am !

Been sufferingS since 3+yo from this neighbour from HELL...
water drippings from laundry , mop,
throw food on furthest edge of the ac ledge,
wash ac compressor n ledges w water hose during non raining days,
water drippings from bedrooms windows,
throw water n a chuck of white tissues on the bedroom ledge till it is black, drop metal pole at 6+am
ETC ...
Really hope jlb gov mandate criminal law to evict neighbours from Hell, high rise litterbugs, bird feeders, irresponsible cat feeders etc from their HDB to mandai forever.