Have you tried a reset.
The jags and vauxhall vectras suffered the same fault.
All that was needed was to wind the window fully down and hold the switch for further 7 seconds then wind fully up and hold for further 7 seconds.
The fault nearly always returned for some reason but only after a few months, but once the owner new the reset proceedure it became an easy fix.
I don't know if this applies in this case but worth a try.