Inexplicable Data Spike

We normally use between 400-600gb/month and have not changed any behavior, added devices or done anything to increase data usage. In April, we were notified that our usage was 3x our average over the past year. And in the first 2 days this month, we’re already over 800gb. I have an open ticket with the Security Assurance Team but judging from previous posts, I should be prepared for a non-solution and upsold to an unlimited data package. Has anyone else had this happen and successfully solved the problem or given a reasonable explanation?