Complex sentence: The BPAY scheme sets an interchange fee, called the capture reimbursement fee (CRF), which is payable by the biller's (the merchant's) financial institution to the bill payer's financial institution.
Split into simpler sentences: The BPAY scheme sets an interchange fee, called the capture reimbursement fee (CRF). The fee is payable by the biller's (the merchant's) financial institution to the bill payer's financial institution.