It is a quite new car - less than 1000 km. Diesel version
It was easy to figure out that it is a ''stick on the right of the wheel'' but it is not quite obvious what move causes back wiper to operate

have you tried pushing the wiper control stick forwards?

There should be either a toggle switch on the dash with a pictogram of a windshield and wiper or else a second rotary knob on the stalk with no intermittent settings. If this does not help, then park the car and try every switch you can find.

it is a twist and push forward/back switch on the right of steering column. like the high beam on lights.

l think if you flick forward the stick for the wipers it should go on and flick it back toward you it will go back. had one last year and i'm nearly sure this is right!