Fraudulent charges

Has anyone noticed extra charges coming from xfinity that aren’t tied to a service. I had to pay my full balance prior to transferring my service, but my first new bill has a “past due charge” of $91. I’ve gone back and forth with agents via web because it’s impossible to get someone on the phone. One agent said they see the mistake and would credit the bill but hasn’t. Now I have to reach out again and fight to get this charge off. I just want to pay my correct amount.