public function getTotalRefund()
    {
        //filter by customer id
        $customerOrders = $this->orderCollection->create()
            ->addAttributeToFilter('customer_id', $this->model->getId());

        $totalRefunded = 0;
        //calculate total refunded
        foreach ($customerOrders as $order) {
            $refunded = $order->getTotalRefunded();
            $totalRefunded += $refunded;
        }

        return $totalRefunded;
    }