I got high data usage even when I was, supposedly, on WIFI. At 4:30 a.m. I'm always at home [iPhone 5S not switching to WIFI?]. At 7:30 a.m. I'm getting my son ready for school and there is a 20 MB usage. I have an iMac on Comcast Internet at home. I will be paying closer attention to my usage and documenting when I have cellular data off. Last cycle I was on 10 GB and I had 3 overages. I paid ~ $250. I lowered to 2GB and I'm at 25% with "21 days left".
Another issue. It says 21 days left even though there are 28 days left. Are weekends free for data? Today is the 22nd and the cycle ends on the 12th.