Citroen Berlingo unreliable electrics?

The heater stopped working on my 2004 Berlingo - I found that thumping the dash just above the hood release catch made it work again - poor connection? Then the horn became spasmodic - seems to only work if you hit the right spot at the right time - latest thing is the indicators only work on the front/sides at twice normal speed - not bulbs as the hazard lights all work fine - any ideas other than buying something japanese next time?