Removed wifi boost wall plug

I had inserted a wifi boost box to have better wifi, not realizing I would be charged for it. I didn't even buy it, my boyfriend did. I can't afford it. I was surprised when I received a bill from Xfinity after being told the Internet was free. Well after receiving the bill and realizing what the charge was for I immediately removed it from the wall plug in. So why am I still being charged if I'm not longer using it?