Spam submission bloating into 50GB

I have no idea why this is happening, but some bot has been hitting links like this 2000 times every 15 minutes:

/?action=export_events&ai1ec_cat_ids=63%2C120%2C62%2C69%2C65%2C81%2C66%2C83%2C72%2C70%2C67%2C78%2C64&controller=ai1ec_exporter_controller&no_html=true&plugin=all-in-one-event-calendar

And whatever is happening, it’s adding 10-20 gigs of files to our caching folder every day.