Visa has some sort of "protection" scheme in place. One of the trip items is a purchase via the internet at certain times of night.
Another one was a number of transactions via the internet in a short period of time.
Other than that Visa would not disclose details.

In the US there can be another problem. Some hobby suppliers have what looks like a domestic transaction via pay pal.
In actual fact, the paypal pay to account may be an overseas account. The buyer doesn't necessarily find this out until the final CC card
billing shows a "foreign transaction" fee, imposed even though the transaction is in US dollars.