what needs to be done as the last step to get the refund?
I found this site, but must admit that final step is a bit vague. It says " To the document there should be attached the receipt from the cash register issued by the seller."
"The tax refund for the travelers is executed in Polish zlotych by the seller or by the entity which area of activity is to make the refund. The refund may be done in the form of cash payment or transfer order, crossed check, or payment card."