Hi @Anonymous User
When you go into My Account > Bills & Payments whilst logged in on here it should show the charges and when highlighting & clicking the charges further it should itemize the charges by clicking on any arrows to show more information on screen.
If the figures are all Broadband & Phone related and not associated with any TV passes then i don't know why you have been charged for further extra months.
Like you said they might be a possible small charge or refund when you switch provider depending on the day when the switch ties in with your final NowTV payment due date, but i wouldn't expect any further monthly payments (i don't work for NowTV and replying back here has a customer).
If you believe the further monthly charges are wrong, then maybe send them some communication on the web form in this link page below.
https://help.nowtv.com/article/how-to-submit-a-broadband-complaint1