re: Why does it take retailers days to credit you back when you return an item?

It is actually the ach system that the credit return must pass thru. The merchants equip.ent handles it immediately, just like a charge....but then it must pass thru a complicated ach (clearing house) between the card issuers and the banking system. There are several entities involved besides the merchant. And after all is complete, then the card issuer can relay the credit an d post it back to your card.

If it were originally a PIN debit trxn, thats different and the store then drives you cash on your return. There is no "un-doing a PIN debit. That would be Kirk trying to stuff money back into an atm.