Credit Score tanked

If i could give zero stars i would. Nothing but a ****. After my account was changed to a month to month account and a cancelled it. I was still told that I owe them money 2 months later. I called to find out why and was told some nonsense reason of window of when i transferred i still had an active account for a week and had to pay that amount. I paid that amount to then be handed over 2 months later for not paying my account. I then call to find out what is happening. And was told they see the note there on the system that it was suppose to be closed and it never was after they already handed me over and my credit score took a hit for no reason.