public function getCompleteReferenceNumber($formatted = true, $fillZeros = true)
    {
        $referenceNumber = $this->getReferenceNumber();
        $notForPayment = $this->getNotForPayment();

        $completeReferenceNumber = $referenceNumber;
        if ($notForPayment) {
            $completeReferenceNumber = str_pad($referenceNumber, 26, 'X', STR_PAD_LEFT);
        } elseif ($this->getWithBankingCustomerId()) {
            // Get reference number and fill with zeros
            $referenceNumber = str_pad($referenceNumber, 20, '0', STR_PAD_LEFT);
            // Prepend banking customer identification code
            $completeReferenceNumber = $this->getBankingCustomerId() . $referenceNumber;
        } elseif ($fillZeros) {
            // Get reference number and fill with zeros
            $completeReferenceNumber = str_pad($referenceNumber, 26, '0', STR_PAD_LEFT);
        }

        // Add check digit
        $completeReferenceNumber = $this->appendCheckDigit($completeReferenceNumber, $notForPayment);

        if ($formatted) {
            $completeReferenceNumber = $this->breakStringIntoBlocks($completeReferenceNumber);
        }

        return $completeReferenceNumber;
    }