private function getExpiredDue($prefix)
    {
        return $this
            ->getExpiredDueQueryBuilder($prefix)
            ->select('SUM(' . $this->getAlias() . '.' . $prefix . 'Total)')
            ->getQuery()
            ->getSingleScalarResult();
    }
private function getExpiredDue($prefix)
    {
        return $this
            ->getExpiredDueQueryBuilder($prefix)
            ->select('SUM(' . $this->getAlias() . '.' . $prefix . 'Total)')
            ->getQuery()
            ->getSingleScalarResult();
    }
Returns the expired due total.

@param string $prefix

@return float