You could try contacting KNF, I wonder what their response would be:
http://www.knf.gov.pl/en/dane_wspolne/complaints.html

You could also fill out this form (use Google Translate; hopefully they employ someone who's fluent in English):
https://www.knf.gov.pl/dane_wspolne/Serwis_konsumenta/pomoc/skarga_na_bank.jsp