Product cancel hook doesn't fire when refunding only shipping costs

[andrewrowanwallee]

We have a use case whereby a merchant wishes to be able to refund only the shipping costs, not any part of the item. We need to be able to register this refund in our payment module but the hookActionProductCancel doesn't fire if no product is being cancelled. Is there a way to hook into shipping costs refunds? Thanks

[andrewrowanwallee]

@prestaforum any ideas?