Car broken into

Our car was broken into again the other night on St Ann's Road. Ransacked the car a bit - but we don't keep anything worthwhile in the car, so nothing taken. And it must've been one of those signal bouncing gadgets used as the passenger door was only half closed when I got in it yesterday and there were no signs of breakage. Anyone else purchased one of those signal blocking pouches and can recommend one? Classic thing too of mentioning it to my neighbour and she said she had seen two people sitting in a car out the front and thought it was odd they just sat there for hours doing nothing... well... turns out they were doing something :(