I paid a past due bill directly to XXXX who instead of applying the payment to the debt, passed the check on to their debt recovery agency Jefferson Capital Systems LLC. XXXX then claimed that my check (a cashier's check issued by XXXX Bank Bill Pay) was returned NSF. XXXX shows the check as being paid. Jefferson Capital Systems subsequently reported the debt as currently due over XXXX months after payment was made, driving my credit score down dramatically. Neither party will acknowledge responsibility for the error and I have not been credited with the nearly $XXXX payment that was made to XXXX. I have been told that the credit agency has XXXX days to respond to my complaint.