Baumatic BDW13 not washing properly/inconsistent?

My Baumatic BDW13 is totally inconsistent - sometimes it washes for ten minutes and stops, sometimes for an hour. The water doesn't always heat up, the detergent hardly ever comes out the dispenser, the dispenser rarely opens, and all the dishes are left with a sticky black spotty deposit. It's all as clean as I can get it, no water in the bit behind the plinth. I thought it wasn't shutting prorperly but I've fixed that but it's washing worse than ever. Any ideas?