Mys wifes Focus, sometimes has a problem with the front screen heater and rear not working, rear wiper sometimes does not work and the heater works only on number 4. which a auto engineer advised was the resistor pack, which I replaced with a new one, but after a week it stopped working again. They also said the emu was the fault with the other issues. I now believe that he meant body control unit. Can anyone suggest where I can get a replacement unit from, how much and are they easy to fit