At close on midnight last night, I received an AWS notification email, telling me that my EC2 budget had passed one of its limits. Since my last budget post, my activity with AWS has been within the CloudFormation services, which is free-tier.
To understand why I was being charged, I checked upon billing info. The results showed that I was still being billed for EBS services.
My conclusion was that I had not completely deleted my EBS volumes during my last attempt. In checking the EC2 service, I was proven right.
This time, I made sure to delete my EBS volumes, and stop the unnecessary credit charge.
My next budget update should only show purposeful charge, which I have initiated.