I have just bought a Renault Espace (the first shape) as it is fitted out for my disabilities, only thing is it can and does cut out for no aparent reason then starts up just as mysteriously again. I have been told is one of these magic boxes(spark amp etc.) how would i go about instructing my sons to mend it, i cannot find anything relative in the Haynes Manual, and i am excessively mean, even if i do say so myself. so i need a cheap fix, any offers?