Hi there.
Have you checked under the ashtray in the center-console for the diagnostic connector? -Normally just lift up the ashtray and you'll see it under there.
If not it is probably under the dashboard (driver side) where the plastic cover ends and over the pedals.
Normally on newer Opel's, if you press the Open-button on the remote for 3 sec or more it will open the windows, close the windows by holding the Close-button for 3 sec or more.
Hope this helps.