You get a message that your card was charged for your monthly fee to something you don’t need or want anymore. You meant to cancel the service, but it’s only a few dollars a month, and you always forget until you get the next message you were changed again.
A service that connects to your cards and an app that alerts you when a charge is being made. You have the option to ok it, or cancel this particular transaction or all future ones as well, with a push of one button. You can set a default for when you are not available.
If you have automatic charges as a merchant (monthly fees you charge your customers), sometimes they are declined. Many of these could be circumvented.
A mechanism that allows you to check a charge in advance without actually charging the card. If you get a reply that the charge will not go through, you can alert the customer before the actual charge is applied to his card. It’s better for the client and you.