Polish DVD available only as part of Isabelle Adjani boxed set
The Polish DVD release of POSSESSION is only available as part of a three-DVD Isabelle Adjani boxed set. Apparently, the film was never released individually on DVD in Poland, so you won't be able to find it if you search under Zulawski or POSSESSION.
The other two films in the boxed set are the early '80s French-language releases DEADLY RUN and NEXT YEAR, IF ALL GOES WELL.
Here's a link to the boxed set on the site of a major Polish online retailer:
http://merlin.pl/Kolekcja-Isabelle-Adjani-pakiet-3-filmow-DVD_SPI-International-Polska/browse/product/2,418063.html