Did not work – got attacked

I added Zero Spam months ago after an attack on a Give WP donation form. This long weekend the site was attacked again and 2000 donations were tried over 4 days. Noone noticed due to the long weekend. Zero spam did not stop it, not sure if there was a wrong setting or something else that let it happen but there should be something that can see that too many transactions in a short period of time is likely to be an attack especially if all the credit card numbers fail. Zero spam did not stop it, the payment gateway did not stop it although they did fail all the attempts and GIVE WP did not stop it.