Does your vehicle have the touchscreen sat nav system? There was a changeover in late 2004 from the BMW non-touchscreen sat nav to the Denso touchscreen sat nav systems. Your vehicle may well be the MY05 model, my Rangie was registered in 2004 (54 reg) and it's the MY05 model, so probably the same with your Rangie.
Does your central locking work at the moment?
As I mentioned, fuse 15 is for power to the front windows, central locking, diagnostics and power assist steering, so this fuse is the most likely culprit in this case.