I've noticed that you get a discount if you have xfinity mobile and certain xfinity packages. I have home, internet and 205 channels, I also have 2 lines with xfinity mobile. It would be nice if I could also get a credit or discount. When I had AT&T, I also had phone ,internet and Direct TV, i got a monthly credit for having cell service with them
The only discount that I am aware of is that you are getting $20 off each line because you have Xfinity Internet. If you were to drop Xfinity Internet they would allow you to keep your XM lines but would then charge you the $20 per line each month.