To convert the band structure file to a file which can be plotted directly, you can use the scriptcp2k_bs2csv.py
from below [...]
gnuplot>set yrange [-8:14] gnuplot>plot for [i=4:23] "WO3.bs.set-1.csv" u 0:i w l t ""
SPECIAL_POINT ??? #GAMA SPECIAL_POINT ??? #X SPECIAL_POINT ??? #M SPECIAL_POINT ??? #GAMA SPECIAL_POINT ??? #R SPECIAL_POINT ??? #M
NPOINTS ???