Change hikashop order status from external code

-- HikaShop version -- : 4.7.3

Hi,
Is there any way to change hikashop order status with an extarnal php code and send the order status email to the user as well?

I make a hikashop webshop which is connected to a billing software which is connected to the bank.
When the user choose bank wire, he got a fee request form (like a pre invoice) and when the transfer is made then the invoice is automatically generated. In this state I have to modify the order status in hikashop to close the order.
I can get the payment status from the billing software and I would like to change the order status in hikashop to completed and send the email to the user.

I hope it's clear, and possible.

Thanks

If I put my code into a function in a hikashop plugin how can I call that from a cron?

I have a hikashop plugin called billing and in the billing.php I made a function updateStatusFromBillingSoftware and put the code below into it.

I'm using the code like this:

$current_status = $bill_api->getDocument($order['order_invoice_number']);

                if ($current_status->getPaymentStatus() == 'paid') {
                    $orderObj = new stdClass();
                    $orderObj->order_id = (int)$order['order_id'];
                    $orderObj->order_status = 'confirmed';
                    $orderObj->history     = new stdClass();
                    $orderObj->history->history_notified = 1;
                    $orderObj->history->history_reason = "Invoice ready";
                    $orderObj->history->history_type   = "modification";
                    $orderClass = hikashop_get('class.order');
                    $orderClass->save($orderObj);
                }

 if($order->order_status != $order->old->order_status){

            if($order->order_status == "confirmed"){

}
}