Here is the proper structure of PESEL number:
It has the form of YYMMDDZZZXQ, where YYMMDD is the date of birth (with century encoded in month field), ZZZ is the personal identification number, X denotes sex (even number for females, odd number for males) and Q is a control digit, which is used to verify whether a given PESEL is correct or not.
en.wikipedia.org/wiki/PESEL
Btw. have you tried a debit card, not the credit one?