Business closed, equipment returned but comcast still billing me for 60 days

My business closed on Jan 31, 2019. I called and got the information and instructions to close the account. Equipment sent back immediately via UPS store, as directed. Account balance was $0. Next month I got a bill and figured being processed. This month got another bill, including past due notice for February.

I called support and they said it takes 60 days to process the closure and that I needed to pay until that closure. Why am I supposed to pay for a business that no longer exists, has no comast equipment and no comcast service for 2 months past the cancellation?! Why would they not make that clear(er) on my account or when I inquired as to account closing requirements, etc.?!

I am going to be very angry at comcast, as a residential customer as well, if I have to pay this money for no service out of my own pocket.