Fake Xfinity mobile account

I use Xfinity for the Internet and the television. I have never used Xfinity for mobile telephone services. I use Sprint which has now become T-Mobile and I still have the same number I have had since 2015. I have called Xfinity and now the collection service that I have been turned over to! All I can figure is that it must be a scam. I do not now nor have I ever used Xfinity for a mobile telephone service. Check your records please. My Xfinity account is and has been paid up. That’s why I didn’t understand this but now I see that someone has set up a fake account I guess. Help!