Xfinity support lied to me on many different occasions

Support told me Xfinity actually owed me money and would refund/credit me. But a few months after cancellation, i get a notice in the mail from collections. I found that xfinity was trying to bill my credit card too, disputed it twice and got it taken down. Xfinity, can you get out of my life? Real question: can you give me the money you said you owed me and cancel whatever you billed me/ tried to steal from me?