I had Verizon Fios Internet for years in New Jersey. March 22 i called them to disconnect it. I was told it was going to be done immediately, 3 days later still wasn't done, i called again and they said it was going to be done on March 26. Same week i received a bill for billing period march 21 to april 20. I called billing department and was assured that because i disconnected it on 22 i was going to be adjusted for a refund for the month i never used.
Next month bill came and same issue, i called again and was told to wait for next bill and surely it will be adjusted. Called multiple times and each time was told the same story. Today July 28 i received a collection call for the amount $119.56 because Verizon Fios never did anything to my bill, they billed me for the entire month of service i never used and added few late fees to that for good measure. I contacted Verizon billing and financial departments and after talking to multiple people and escalating the issue to supervisors i was told that Verizon Fios "does NOT" give money back on their Fios Internet service. They told me that even if i am one day in the new billing period i was not going to get a refund for the remaining period because that is the way they do business.
For good measure i contacted BBB, FCC and New Jersey Attorney General office, hopefully one of them can fix it since Verizon employees can not.
Technically you are paying a month in advance. When you terminated service after your bill closing date Verizon charged you for the month. You could have paid that invoice that covers you until the closing date of the next month. This way you owe them nothing.
You may not get the money refunded in that case. And the account was not closed again through the next month. So two payments not made add in late fees and then collections.
Read this link. Verizon Fios Terms of service