Product: Debt collection

On XX/XX/XXXX, I received a notification from XXXX that PlusFour Inc. had filed a Major Derogatory on my credit history. I am furious because I have excellent credit ( i.e., XXXX score in excess of XXXX ) and have been working since XX/XX/XXXX to have PlusFour provide me with evidence or proof that this claim was mine, as I NEVER RECEIVED AN INVOICE from XXXX XXXX. PlusFour had never responded to my certified letter, and when I called PlusFour they was unable to provide me with invoice numbers from XXXXXXXX XXXX, the name of the physician who authorized the test I was being billed for, or the medical insurance codes for the services. As I had disputed both claims for the reasons above and had not heard back from PlusFour, I assumed that the issue had been resolved with the information I provided when I disputed the claims. Obviously, it was not and they filed a Major Derogatory on my credit history. 

Here is the chronological summary of my disputed claims : Late XX/XX/XXXX Received a collection notice for {$460.00} from PlusFour ( no date on the notice ). 
XX/XX/XXXX Sent PlusFour a certified letter ( see attachment ) disputing the claim ( Reference XXXX ) and explaining that I had NEVER RECEIVED AN INVOICE from XXXX XXXX The letter explained that I thought it could have been an insurance billing error with XXXX XXXX XXXX and I provided my insurance information. 
Late XX/XX/XXXX Received a second collection notice for {$1200.00} from PlusFour ( no date on the notice )! 
XX/XX/XXXX Around XXXX received robotic generic call from PlusFour. Around XXXX I called PlusFour and spoke with XXXX XXXX I explained to her that I had sent a certified letter to PlusFour regarding the collection notice and had not gotten a response but instead received another collection notice. After about a twenty-minute conversation XXXX was able to determine there were now two different collection claims ( Reference numbers ending XXXX ( from XXXX ) and a new one XXXX ( from XXXX ). ) I asked what these were in reference and she said that she didnt have that information. She could not provide any information regarding the original invoice ( s ) from XXXX XXXX ( which I never received ), any information regarding what physician had ordered the tests, and could not provide me with any medical billing codes. She did acknowledge that it was in their system that I had disputed the first collection notice. I advised her to put in my records that I was also disputing this second claim. I reiterated that I had never received an invoice and I needed to know specifics about their claim to know that it was even my bill. 

So, in summary, what PlusFour has done has sent me two collection notices, which I have disputed and asked for specifics to verify that they were legitimate charges. PlusFour never provided that information, they just filed a major derogatory on my credit record. Why I also dont believe these are my charges is because I have used XXXX XXXX for my annual XXXX. and my doctors gets insurance pre-approvals before XXXX XXXX would allow me to schedule, then I go for the tests. After the tests, if there was a nominal amount due, I would receive an invoice from XXXX XXXX and I would pay it. This normal process has not happened and that is why I suspect insurance fraud. Why else would my certified letters and calls disputing the charges be ignored? 

I am asking PlusFour to IMMEDIATELY REMOVE the major derogatory from my credit report! This has major economic and reputational repercussions such that that I would be compelled to hold both PlusFour and XXXX XXXX responsible for both economic and reputational damages if this remains as any part of my credit history.