public function getCustomerOutstandingInvoices($code = null) {
		$subscription = $this->getCustomerSubscription($code);
		foreach ($subscription['invoices'] as $key => $i) {
			// if the billing date is in the future or has been paid
			if ($i['paidTransactionId'] || strtotime($i['billingDatetime']) > time()) {
				unset($subscription['invoices'][$key]);
			}
		}
		if ($subscription['invoices']) {
			return $subscription['invoices'];
		}
		return false;
	}