Need some help. Have this code in `PaymentModule.php` in Prestashop:

```
$params = array(
    '{voucher_amount}' => Tools::displayPrice($voucher->reduction_amount, $this->context->currency, false),
    '{voucher_num}' => $voucher->code,
    '{firstname}' => $this->context->customer->firstname,
    '{lastname}' => $this->context->customer->lastname,
    '{id_order}' => $order->reference,
    '{order_name}' => $order->getUniqReference()
);

```

I use `$params['firstname']` for showing customer `firstname` and get nothing. I insert `$params['firstname']` in `/modules/bankwire/bankwire.php`

Please tell me where I make a mistake?

Thanks