Product: Debt collection

I held a XXXX residential internet account for 2 years that was added to a well-established existing XXXX wireless ( cellular ) service under a one-bill payment program. A couple of months before closing the XXXX residential internet account in XXXX of XXXX, the one-bill payment program was eliminated without my being notified. Consequently, I was behind in my payments for one month. At the end of the following billing cycle, I was notified I was past due when the current bill came and I contacted XXXX residential customer service to correct the situation and paid the account up to date. In XXXX, XXXX, I closed my residential account as I was leaving the area to travel indefinitely and paid the account in full as is required to close the account. 
In late XXXX XXXX, I received a notice that I had a balance of {$160.00} in collections. I contacted XXXX 's residential customer service again to resolve the issue and none of the multiple representatives I spoke with could identify the source of this past due amount. They referred me to the XXXX wireless customer service department which was also unable to identify or account for the past due amount. Ultimately, I spoke with a manager who, being unable to confirm on their end the funds were absent, agreed I should and would not be held liable for the amount in question. She assured me she would update my account accordingly and relay the information to the collection service. 
Late XXXX XXXX, I received another collections notice from XXXX XXXX concerning the same {$160.00} that I was assured had been resolved months ago. I spoke with a XXXX rep on XXXX XXXX who was unable to help me as XXXX is only carrying out the collections process of a billing error originating with XXXX. So I contacted XXXX 's residential customer service department once again. After repeatedly explaining I needed to speak with a manager and that XXXX would not be able to help me as the problem originated with XXXX, the representative still transferred me to XXXX to sort out the situation, citing that the account had been purchased by XXXX rendering XXXX unable to help me. 
Fast forward to XXXX, I 've received what I believe is now the XXXX collections notice ( each of which came from different agencies and none of whom could identify the source of the debt and all of them received my dispute information and agreed I was not liable ). I do not have all of the collections agencies names as some of my paperwork was lost in my most recent XXXX move but I do have the letter disputing the XXXX claim, a claim I received from the XXXX or 5th agency XXXX and the contact information for First Credit Services, the most recent agency that has acquired my phantom debt. 
I do not have a problem with the tactics these companies have used to collect this alleged debt. I do have an issue with it 's continued transference from XXXX agency to another in the face of my repeated attempts to dispute it and their repeated acceptance of and agreement with my evidence. 
During my search for information concerning this issue, I 've found countless other XXXX account holders who experienced the same exact problems. Whether it has perpetuated itself as long as mine has or they just gave up and paid I can not say, but I will not pay twice for a service when I have proof I paid it the first time.