PHP radio button condition

[xamonix]

Hi

I'm trying to modify a Shipping module for an online shop but I'm not getting it to work...I want to put two options on that, if customer chooses first option he gets one price for the shipment if he chooses second option then he gets a different price.

 

The original module only allows one option for Shipment Method and I want to add a second option using two radio buttons.

 

Basically I want to check what radio button is selected and then get the value, if first radio button is checked get it's value if the second radio button is checked get the previous value plus and aditional tax.

Here goes the code:

 

 $_SESSION[$value] = "1";
      $string = " <input type=\"radio\"  id=\"radio1\" name=\"shipping_rate_id\" value=\"$value\" />";
      $string .= "  Zone Shipping -  $country_name <strong><div class='zone'>". $CURRENCY_DISPLAY->getFullValue($rate )."</div></strong>";
      $string .= "<br /> <input type=\"radio\"  id=\"radio2\"name=\"shipping_rate_id\" value=\"$value\" />";
      $string .= "  Contra Re-embolso (+ 1.50€)<strong><div class='zone'>". $CURRENCY_DISPLAY->getFullValue($rate+1.50 )."</div></strong>";
      echo $string;
    }

  function get_rate( &$d ) {	
      
  if (document.getElementById("radio2").checked) {
      $shipping_rate_id = vmGet($_REQUEST,"shipping_rate_id")+1.50;
  $zone_arr = explode("|", urldecode(urldecode($shipping_rate_id)) );
  $order_shipping = $zone_arr[3];
      } else {
  $shipping_rate_id = vmGet($_REQUEST,"shipping_rate_id");
  $zone_arr = explode("|", urldecode(urldecode($shipping_rate_id)) );
  $order_shipping = $zone_arr[3];
   }
  
  return $order_shipping;
  }