Refund not processed, sent to cancellations

I had an account at a prior address.  Xfinity didn't cancel on time despite multiple asks.  When they finally did cancel, they promised me a refund for the months I was billed that had 0 usage.  This has been escalated twice, but I never receive the promised callback from the supervisor.  Today, I received a phone call from collections regarding the months that had zero use.  I'd really like you to settle this as promised before I escalate to the Attorney General's office.  You are acting in bad faith to make your products almost impossible to cancel, and if you didn't intend to refund me, you shouldn't have promised to do so twice.  Please refund my account and cancel the collection immediately.  Please contact J. Hill on my account at that number if you have further questions, or give me a direct line to the correct staff member to fix this.