Xfinity mobile charges 1729.00$

I Was charged over $1729.00 for XFinity Mobile services , and I’m not even an xfinity mobile customer, they cannot find anything in my internet account where I signed up for any services, but the bank statement clearly says XFinity Mobile 1888***-****, PA . I never authorized the charge or gave them any card #, what do I do? My bank says contact XFinity, XFinity says contact your bank, etc, etc.. it’s very frustrating and that’s a a lot of money.