Send Alert to Admin when Subscription Cancelled by Customer

I would like to request the ability to get a notification when a customer goes into their account and turns off a subscription.  Our system requires manual deactivation of services when this occurs and if we do not know when a customer does it, we don't know to turn off services.  This seems much more important than other features already in place like notifying an ADMIN when a credit card is updated.

Thank you.