On the main drag. Take a ticket for queue control from the box inside the main door and wait for your number to pop up in the respective window. When taking your ticket, choose from (a) cashier for paying bills etc at windows N°2-6 (b) parcels at window N°12, and (c) letters and stamps at windows N°13-20. Collect post restante letters from a separate entrance on ulica Pocztowa.