Billing dispute. Bill says I am renting a router/modem when I am not

I recently changed plans. My old plan was the old 1200 mbit down and I switched to the new 1 gig unlimited. On both plans I used my own gear and have never rented equipment from Xfinity. When I go do the devices page on the website it doesn't show any, yet I am being charged a rental fee. What's going on and how can I fix it? The stupid AI bot is no help.