Account cancellation - 3x and multiple months still not right

I am unable to cancel my account, and am continually billed even though I get cancellation confirmations. I originally cancelled for May 26th, but the rep said that cancellation was closed because the owner of the home I had sold my house too, had requested to set up service. Ok this would seem to be a pretty standard thing so not sure why my service was not cancelled (I just found this out). Account continued to bill me, and I used the message ability to talk with a rep to confirm cancellation on June 20th effective immediately since they couldn't backdate it, got the confirmation email again and still it continued to bill. I did get automatic payments turned off on the 26th call, so atleast it is just racking up outstanding balance. I also contested the last month charge with my CC company to get my refund. 

I called yesterday (July 14th) when I got another bill notice for August, and the rep said it was taken care of it and I would see immediately a different balance or credit on my portal... nothing has changed. 

Canceling this service has been the biggest pain, and it should not be. Who do I have to message to actually get this corrected? I do not want the non payments to reflect on my credit, as it is only Xfinity's issue and nothing to do with me. Do I have to get a lawyer involved as this seems to be predatory business? Just beyond frustrated.