I had the same problem - Maplin tech said same thing as Crabby. You can check if the car cuts power to the unit by seeing if the red flashing light behind the face-off goes out when the car is turned off. If it does then you need to look at the wiring, if not it's something else. This might seem a bit like a low-tech fix, but I fixed mine by holding the radio station/frequency 'location store' button (1-6) down for several seconds after beep that supposedly confirmed the save. Letting the button off straight after the beep only saved the stations until the car was turned off - holding if for much longer has so far saved them for 2 days.
Stilly
June 2008