Product: Debt collection

I am making a formal complaint because I am being sent to a collection agency named Diversified Consultants, INC. by XXXX XXXX XXXX. The debt their claiming I owe of {$260.00} has been proven to be paid multiple times both verbally & by fax from my bank. I have spent over XXXX hours on the phone with XXXX XXXX XXXX disputing this. I have given them every form of proof that the debt was paid on XX/XX/XXXX, XXXXThe first collection letter I received in regards to this was dated XX/XX/XXXX, almost 7 months after the payment was made. Everytime I prove the debt has been paid, they come up with yet another excuse as to why I supposedly owe the debt. I have been told the payment didn't go through, the payment wasn't received, the payment was reversed ect. They then told me this past Friday, while my bank was on a conference call with them, to dispute the payment through my bank. Which then would cause XXXX XXXX XXXX to return my money & then I'd have to turn right around & pay Diversified Consultants, INC. to make the debt clear. That was what XXXX XXXX XXXX advised me to do while my bank was on the phone & they assured us this would clear all debt & both my old account & my current account would be back to normal. I then received a call from XXXX XXXX XXXX this morning stating that my payment made on XX/XX/XXXX of {$260.00} was supposedly transferred to my current account on XX/XX/XXXX. Mind you, I was not told this was being done, nor did I give them permission to do so. All I did was call asking why my bill was so high & they stated it was because I had missed a payment. When I proved to them I hadn't missed a payment they stated that the payment made back on XX/XX/XXXX was posted to the wrong account so they were going to rectify it. They then said if I continue with the dispute through my bank that they will place my current account in default & I will have to pay that amount back, to both accounts, basically paying twice. I have been called ridiculous, incapable of understanding anything, ignorant & told to shut up & just pay the amount I supposedly owe. Ive been transferred multiple times per call, I've been hung up on, I've been told I was being transferred to a supervisor/manager & then either hung up on on or told they were busy on other calls & they would call me back but never once was I called back. I've been the one to make every attempt to rectify this but they wont budge. I've spoken to Diversified Consultants, INC. and they advised me to email them the proof from my bank that the debt had been paid, which I did immediately. The gentleman on the phone from diversified said that they will clear the debt through their company but that XXXX XXXX XXXX owns their company & multiple other debt collection companies & most likely XXXX XXXX XXXX will just have another one of their debt companies come after me for the amount they claim I owe. I just want this debt cleared, I want XXXX XXXX XXXX XXXX XXXX & all other companies they own to know they can't take advantage of people & continuously get away with it. My XXXX is through the roof, I'm XXXX XXXX from the stress of all of this & I want retribution. I'm begging for your help with this, please help me show XXXX XXXX XXXX XXXX all their subsidiary companies that we matter & they cant take advantage of us anymore!