I'm trying to connect up a new Bosch oven (HBN560550B). The cable 'chamber' and the cable clamps themselves have non-standard screwheads - one's a star shape, the other is very irregular in shape. Does anyone know where I can get suitable screwdriver heads? Bosch themselves is a thought but I can just hear them saying \\\"Authorised installers ooon-leee!!" Thanks D