Fios Mess... - Cable modem owned and not charged for acct. Renewed acct charged for my owned modem

Fios messed up my acct. Shut down my old acct even though I never asked for it and forced me to set up a brand new account. On the old acct, my modem was NEVER charged. I owned it. 

Now, with the new acct, they are charging me $12/month for it. Not sure how long they've been doing it. But, I pay automatically. So, just never really noticed it much. The bill is already WAY too expensive. $12 slips under the radar. 

Support is making me jump through hoops to prove that I own it. And, I know I've read a lot on this forum about stolen modems and scams. However, if this wasn't a problem for 12 months with my old account, why is it a problem now?