Just on the point of how the damage happened to the cupcakes, would it be possible that this happened when the customer was taking them out of the box and putting them on a serving plate? The reason I ask is because stiletto cupcakes are made in three parts - the cupcake (front of the shoe), the sole and the heel. Unless you've made them yourself, a customer might not understand that they come apart fairly easily and the damage might have been done lifting them out of the cake box.
I'm not sure if this is even what happened, but I'm wondering if the solution could be to have each cupcake on it's own miniature cake card (just cut a standard sized card into individual sizes) and secured in place with a little extra dab of chocolate, under the toe and under the heel. This way each stiletto cupcake can be lifted out of the cake box by it's card.
Or does anybody have any better ideas for improving the stability of high-heel cupcakes? And engineer/cake decorators out there??!!!!