Car Owners Hub UK - Built by Drivers, for Drivers

Greetings, gentlemen. The windshield washers on my wife's 330e (22 plate) stopped functioning today. That can't be it because the reservoir bottle is full. Neither the jets nor the wipers are functioning, even though they seem to be linked. The sound of the motor trying to start up is intermittent before it finally stops.
Do you have any suggestions?

The water stops flowing because black mold has grown in the bottle and gotten stuck in the filter.

So, does anyone have a clue how to remove it? Is it a pressure hose of some kind?

If you can empty it, fill it with warm, boiling water and dishwashing tablets; this should clear it. To fix it, just pop the pipe off at the joint and blow back.

Using hot water and all that guck, the dreaded black gunge.
All sorts of things were tried, including putting drain cleaner in the bottle and extending the pipes to divert any fluid away from the paintwork.
Eventually removed it and cleaned it with a jet wash (I had a spare bottle on hand, so I swapped it out quickly; however, I did acquire a clean one for use in the future).
Once you get it fixed, use only one brand of screen wash. Some people recommend BMW products exclusively, but I've had good luck with tablet-type washes (I bought a 100-pack), so I should be good to go.