[MickH]

From your described problems it sounds as though your charger is installed on your house distribution system RCD and not on a dedicated RCCB specifically designed for the equipment it is supplying. Or maybe the dedicated circuit RCCB is fed from a CB on your distribution board backed up by the distribution board RCD hence your problems. Household Dist Bd RCD's are not designed to handle the EV charging systems because of the AC/DC switching impulsing involved hence the dedicated circuit and RCCB which is designed for this type of load.