Incorrectly sent to collections

I was sent to collections by Xfinity, supposedly, but every single agent I speak to at Xfinity has reassured me that there is no balance, that nothing has been sent to collections, and they have looked through my account all the way back to 2013 and 2 addresses. I am also on autopay so it makes no sense. I attempted to dispute the charges with the collection company and the Credit Bureaus, but they keep indicating that this is a true debt and will not remove the account. I heard from many people that this is not a unique experience and so many people have had this same thing happen. I am at a complete loss at this point on how to get this resolved. It is hurting my credit, and I cannot get a resolution.