Drupal Commerce custom Coupon Type not discounting I'm trying to create my own coupon type so that I can give it a name that will appear in the checkout and add features such as expiry date and product reference. I have been able to add the features to the "percentage amount" coupon type and if I only had one coupon type I'd just change the display name of that, but there will be many coupon types in my shop. Each is a one-time use coupon that a major client can give to their members so there would be types such as Ford-employee-discount and Toyota-employee-discount with individual coupons trackable to individual staff. So even the coupon code wouldn't be good enough to display because it will be something like "F_Emp-JH6d98"

So now that I have a new coupon type I have duplicated all the fields from percentage coupon type but when I get such a coupon added to a bill the "Granted amount" is blank. No discount is applied but the coupon is there on screen and listed as used by the database.

I'd prefer to be able to add a display name field to the coupon type and set it for each coupon I issue (which are made in batches by the Coupon Batch module), but without modifying the Coupon module I can't see how to display the value of that field in the right places.
You may need to implement 

hook_commerce_coupon_granted_amount_alter

to add your granted amount to the display there.

e.g:

/**
 * Implements hook_commerce_coupon_granted_amount_alter
 */
function MYMODULE_commerce_coupon_granted_amount_alter(&amp;$amount, $coupon, $values) {

  if ($coupon-&gt;type == 'my_coupon_type') {
    $order = commerce_order_load($values-&gt;order_id);
    $order_wrapper = entity_metadata_wrapper('commerce_order', $order);
    $coupon_wrapper = entity_metadata_wrapper('commerce_coupon', $coupon);

    // Do stuff to get amount from coupon...
    // ...
    // ...
    $amount = 1000; // example
    $currency_code = "USD";
    $amount = commerce_currency_format($amount, $currency_code, $coupon);
  }
}