Comcast the worst company ever

Our area is unfortunate to only have Comcast as the only internet/Cable/ Phone company. They have tortured us mentally and we can't just deal with it. We disconnected the service back in April and decided to stay without and they are still billing us over $300.00 from their collections for their things that we returned. We have called tons of times and we are lied to that the issue should be resolved in thirty days, just to receive another bill from Comcast collections. Who can we talk to because we are tired of their customer service that no-one seems to know what they are doing and their records seem to be different depending on who you talk to. C'mon Comcast, it feels like service in the middle of the Amazon, wake up.