Surely the fuse value in the plug or FCU is dependent on the CSA of the flexible cable! 0.75mm² means 5A, 1.0mm² 10A and 1.25/1.5mm² 13A. However, as 0.75mm² is rated for 6A continuous, I would suggest that a 7A fuse would be acceptable to allow for inrush currents which might degrade a 5A fuse, and cause premature failure