My windscreen wipers work with no key in the ignition...how can this be fix?

I have a All New Focus Estate LX, 1.6 Ti-VCT 16V 115PS Stage 5 speed manual (2005) which enjoys wiping the front windscreen when i take the key out of the ignition. This happens at random times. eg i could park up go somewhere for a couple of hours come back and the cars windscreen wipers are wiping away inside the car alarms are beeping and occassonally the hazard lights flash. This has happened 12 times now having replaced the battery, windscreen blades, the dealers dont seem to have a clue, or maybe they just like taking my money. Is there anyone out there can help me please..