Final Bill Payment Options

Has anyone else had issues with paying their final Verizon bill?? I paid my Verizon bill online, using the same log-in information consistently for 7 years. When it came time to pay the final bill, I was able to log-in as usual and see the correct pro-rated amount due. I promptly paid the amount due, as usual. One month later, I received subsequent emails that I was receiving a refund check in the same pro-rated amount, and still had an outstanding balance for the pro-rated amount. I called Verizon and they stated they would be able to apply the credit to the outstanding amount. Two weeks later, I logged back in, and found an amount due. I also received a check in the mail. When I attempted to make a payment online, the balance shown is $0. I tried calling customer support, and was told I had to pay over the phone via automated system, which costs an additional $3.50. Why can't I pay the final bill online? Verizon is basically charging a fee for cancelling their services. Ridiculous.