It's approaching 9pm and my neighbours' washer/dryer is still going. Now over 3 hours.

Ongoing problem. If I say anything then they'll find something else. In the short time they've lived above me, I've complained about tv being too loud (so loud they didn't hear me knocking door!), visitors' cigarette ends and beer bottles dropped into my garden. Nearly cut my hand on pieces of glass in the flower bed. Bizarrely, even found two eggs in my compost, presumably dropped from their kitchen window. Solved that too by moving compost bin.

Pet peeve = inconsiderate neighbours!!