Billing

I disconnected my Xfinity account after learning my internet price would jump. When I disconnected the service, I was informed that I had an amount due of $24.67. I paid this amount. But now I am continually billed. Currently, I have a nil of $77.33. I called customer support a number of times and each time I was assured the problem with billing would be corrected in a few days. However, the bill remains. Please help! I feel really frustrated that this billing issue is not corrected dispute numerous calls to customer service. Thank you for your time.