I've noticed all my bank apps on my phone now allow you to create notifications for things like if you account goes under a certain $ amount, if there is a deposit, or like my Capital One card, anytime I use it, the Capital One app pops up a notification on my phone showing me that transaction. I think its a great safety feature because if I all of a sudden so a charge pop up and I'm sitting at my desk, I can know right away someone who is not me is using my card.
If you have your banks app on your phone, check the Notifications or Security sections of the app and you may have some features to turn on.
I agree with you though, $18K is ridiculous. You'd think at like $2K their system would have said "Maybe we should contact this guy to see if these are legit charges."