Only Heyah (787, 788, 880, 886, 888, 889) and Sami Swoi (885, 887) have exclusive prefixes. Rest of prepaids and postpaids in one network have same prefixes (eg. Plus and Simplus have same prefixes).
EDIT:
Here you have all polish prefixes:
http://pl.wikipedia.org/wiki/Prefiksy_GSM
As I see there 36,6 also have own prefix (725, here marked as 36i6)