Ok, so ended up chatting with a manager and we agreed that we cannot tell what caused the issue. To complicate things this happend at the changeover to a billing cycle (which was part of the reason I didn't see the 100% usage email).
They have agreed to give me a one time credit for the overcharge. We've agreed to watch if it should happen again (this happend end of May) and will dig into it right away.
Our modem is the Hitron CGN3 and I've realized "WAN recieving" and "WAN sending" in the status are our actual usage as I also have monitors on all our computers. They all agree we used downloaded about 2GB yesterday while rogers says 90GB! Now I know it has nothing to do with our side of things.
I honestly don't understand what could be the reason for all this. A few days ago I reset the CGN3 to factory defaults and then proceeded to manually change everything back to what they were. There has been no extra usage recorded ever since. The same thing was happening last month when we were on the old Express plan and had the older modem. Again things went back to normal after the factory reset.
It might have been that the modem was stuck on requesting some data over and over again but why didn't a simple reboot fix it?We also never had this problem before last month. Why would two different modems show the same behaviour? What is there to stop it from suddenly happening and me waking up to 200GB gone in half a day?
Did you do any REBOOTS other than the factory resets?
Wonder if it was some device.. which the reset obviously disconnects it.. and reconnects after a time period, then starts its usuage.
I have so far used, the Cisco, SMC, and the CGN3, and have never had any overage amounts (other than the ones i know were ME doing it per say (like 53g upload usage one day from leaving a heavy torrent on with high upload settings... ooops))
Yes I did reboot but only factory reset worked. What device could it be? I monitor all our devices and some hacker using my wifi would still be able to do it since I didn't change the password.
All depends on what you have connected?
Phones, you can usually monitor the usage on them.
PC's you can get software to monitor on them.
But there are other devices which MIGHT connect to your wireless, if you have them. (which can do downloads, etc)
Network attached hard drives, network printers, etc.
Smart TV's, some surround sounds.
Ipods, tablets, etc.
All in all, i would recommend changing the SSID name, the password, etc.. JUST to make sure.
(make sure to change the default rogers login as well into the device)
One potential area of trouble I haven't heard many people talk about here is cloud storage synching processes that might be in effect on a computer such as Microsoft's Onedrive, Google Drive, Dropbox, etc. If these are in use, they are active in the background. Occasionally I've seen them fail in the sync process and data can be re-sent over and over again, sometimes adding up to many gigabytes.