Real - Time Notifications for Cancelled Orders

[FlavaWings]

Hello,

For online orders at my restaurant, we have had customers place online orders, then cancel them after we have accepted them at the restaurant.  The problem is, we do not receive any notification of said cancellation and proceed with making the order.  When we notify the customer that their order is ready, the customer tells us they cancelled the order.  We then confirm this in reports, but we've lost product. 

How can either:

A - The functionality for customers to cancel orders online be disabled, thus making them have to call in to cancel their order.

OR

B - We receive a notification on the POS that an order has been cancelled, thus preventing us from making the order and losing product. 

Thanks!