Oh dear I seem to have joined the club. Central locking not releasing on n/s sliding door accompanied by door open indication even though the door wasn't opened. Left it with VW Stoke overnight as frost was forecast. The following morning the technician experienced the same problem, but "couldn't" do anything because it didn't generate a fault code!
(well he did do one thing, he adjusted the striker plate and make it worse; but that wasn't obvious when I collected it because by then the temperature was well above freezing)
Will try VW Assist route next time.