Frontier Charging after service cancelled and for service not authorized by me Cincinnati Ohio

In early July I called for information on how to cancel Frontier service and port my number to another carrier. Spoke with many persons who could not tell me process. Wanting to complete this before the end of paid up billing period the 18th, I called Tracfone and they sent order to frontier. I called frontier on the 17th and was told order was received and I was paid in full. Bill's continued to arrive for this cancelled service. Then bills started to arrive for account with another number. I contacted them immediately to tell them I had not asked for, authorized, or received service on the number listed on this bill. I continued calling them every month when additional bills arrived explaining not only the cancellation but also the bills sent for bogus account. One of last contacts said acct. was backdated and closed and gave me a confirmation number. In November, they turned the bogus acct. over to collection which I disputed in writing. I have written Frontier as well with complete timeline and names of the more than nine people I spoke with over the months of attempting to settle the matter. Today, Nov 26, I received another bill. I refuse to pay for service cancelled, confirmed, and service never authorized. I assume they don't want to easily allow customers to leave. I also assume someone on commission to sign up new accounts, created an acct I did not authorize.