public function makeBackendFilterChargeAmount($amount)
    {
        $defMin = $this['limits']['charge_amount']['min'];
        $defMax = $this['limits']['charge_amount']['max'];
        return function ($backend) use ($amount, $defMin, $defMax) {
            // temporary hack for now to correct min value for instalments to 500000
            if ($backend->type == 'installment') {
                $min = 500000;
            } else {
                $min = empty($backend->amount['min']) ? $defMin : $backend->amount['min'];
            }
            $max = empty($backend->amount['max']) ? $defMax : $backend->amount['max'];
            return $amount >= $min && $amount <= $max;
        };
    }