To both of my accounts, they changed the date for both to come out of my checking account

Hello, @user_vbi5as I like my payment withdrawals coordinated as well. Currently, Xfinity Mobile customers cannot change their due date. To change your due date for Xfinity Internet, Home, TV, or Voice accounts, follow these steps:

1. Sign in to xfinity.com with your Primary Xfinity ID.
2. Click the Billing card or Billing & Pay and select View Bill & Transaction History.
3. Scroll to Bill Settings and click Bill Due Date.
4. Choose a new date from the drop-down menu and click Continue.
5. Review your current and new due dates, then click Submit to finalize the change.

Note: You must have completed one billing cycle and have no past due balance to be eligible.

For more details see: https://www.xfinity.com/support/articles/due-date-change