False charges from Xfinity

I am [Edit: "Personal Information"]. I have been dealing with false charges, non stop phone calls, and bills from Xfinity when I canceled 3 months ago. Now for some reason I have been messaged that a charge is going to a collection agency. I have to deal with these false charges by filing a report through my credit card company because no one at Xfinity can seem to be a man/woman of their word. When I originally canceled I had already paid for a month but only used 3 days which I was told I would get a refund for the remaining of the month but didn’t. Then I was told I had a month to return the equipment or i would be charged.  I returned it within the time period and still get calls about it not being returned. Xfinity please fix this. I’m hard working and don’t deserve to be scammed out of the money that I make just because you are a big corporation.