Our Comcast plan has a monthly data usage of 1.2TB. We rarely go over 600GB in any month but month we nearly hit the limit. I was looking through the router logs to see what was going on and it turned out that somehow one particular Instagram video my spouse was watching would consume huge amounts of bandwidth when the channel was live streaming!

crazy solution that might work for you: open an incognito browser and check for deals for new customers. "someone" I know was able to switch from a $50/1.2TB limited 300mbit plan to a $45/unlimited 1Gbit plan doing this.

if they have a better deal for new users: sign up for a new account under someone else in your household, and cancel your old account after you get your new account hardware setup and working.