设置最小购物车$ value - opencart v2.0

I have seen a year old thread for this (and responded in the wrong place - sorry) Opencart minimum order price

I have opencart V2.0 - I looked at catalog\controller\checkout\checkout.php and inserted the code near the top of the page (as per below snippet). This does halt the checkout process -but when I have a total greater than $25 the warning is still displaying and still stopping the next step in the checkout process. I'm not sure what is the next step to get this right, or even if it should be in another checkout file ?

Your help on this is appreciated.

if ((!$this->cart->hasProducts() && empty($this->session->data['vouchers'])) || (!$this->cart->hasStock() && !$this->config->get('config_stock_checkout'))) {
      $this->response->redirect($this->url->link('checkout/cart'));
}

/* new code to set a mimimum shopping cart value of NZD $25.00
if ($this->cart->getSubtotal() < 2500){
    $this->session->data['error'] = 'Please note: there is a minimum shopping cart value of $25.00 before shipping and tax for you to proceed to checkout.';
     $this->response->redirect($this->url->link('checkout/cart'));
}
*/

    // Validate minimum quantity requirements.
    $products = $this->cart->getProducts();

Thanks.

Replace this line :

if ($this->cart->getSubtotal() < 2500)

To :

if ($this->cart->getSubtotal() < 25)