said by geek_guy:20gb download and 4gb upload
That looks like bittorrent-style usage.
1. Your MAC has been cloned and you're paying for someone else's usage
2. Someone in your household isn't being totally up front about their online activities
3. Both of the above
For sure, just to eliminate the cloned-MAC issue, swap your modem out at the Cogeco store. Brace yourself for a big Cogeco bill.
Have a town-hall with your fellow dwellers and a'splain it to them.
Consider switching your internet to a TPIA provider, like Start or someone else, which comes with much higher caps and usually lower prices. That way you get a new modem out of the deal too.
Mike