Product: Credit reporting, credit repair services, or other personal consumer reports

I am writing to denounce the malpractices I was recently subjected to by XXXX XXXX. On XX/XX/XXXX, I called XXXX XXXX and spoke to XXXX of their agents to request an extension for the month of XX/XX/XXXX and XX/XX/XXXX. During the call the employee advised me that I still owed {$200.00} for the month of XX/XX/XXXX and asked if I could pay the remainder of XX/XX/XXXX and then she can process the request for the extension, which I did. So I paid the {$200.00} for XX/XX/XXXX and the employee processed the extension for the month of XX/XX/XXXX and XX/XX/XXXX ( at least that was what she advised me ) and  she even stated that my next payment due is XX/XX/XXXX. On XX/XX/XXXX my credit was flagged 30 days past due for {$200.00}. So I called XXXX XXXX and spoke to another agent who advised the extension placed actually covered XX/XX/XXXX and XX/XX/XXXX. I advised the agent I didnt need an extension for XX/XX/XXXX because XX/XX/XXXX was already paid. The extension I needed was for XX/XX/XXXX and XX/XX/XXXX. She passed me to her Manager XXXX who tried to tell me that according to their policies since there was a balance for XX/XX/XXXX the extension was automatically applied for XX/XX/XXXX and XX/XX/XXXX. I advised her the same I did to the employee, that as she can see in the record there was a {$200.00} paid the day I called to request the extension, specifically to cover XX/XX/XXXX. So XX/XX/XXXXwould have been a {$0.00} balance and then extension should have been for XX/XX/XXXX and XX/XX/XXXX, and if I knew the extension was not for the month I requested I would have declined the extension or made other arrangements. But from what her employee noted on the account and stated to me the extension was for XX/XX/XXXX and XX/XX/XXXX. XXXX then advised she will go back and listen to the call and I have to follow up with her in 48hrs. I called back on Friday, XX/XX/XXXX and spoke to XXXX, not only she had not listened to the call but she tried again to put the blame on me stating that the extension was for XX/XX/XXXX and XX/XX/XXXX. I went back and forth with her and once again she advised she will go back and listen to call and call me back. She called back a few hours later and advised she had started to listen to the call but refer my acct to their account maintenance department for them to look at the account and see what happen. I advised her I was in the process of buying a house and I was 2 weeks away from the closing date and I need this matter resolve asap. I even asked if the extension was applied for XX/XX/XXXX and XX/XX/XXXX then the payment I had made to cover XX/XX/XXXX should have been applied to the month of XX/XX/XXXX and therefore for I still dont see why they reported 30 days late payment to the credit bureau. On XX/XX/XXXX XXXX XXXX has taken again to step to Flagg my acct to the credit bureau for 30 days late payment. 
I called back on Monday XX/XX/XXXX, I spoke to Supervisor XXXX, who now is telling me that the {$200.00} payment was applied to fees that were on the account instead of the payment. Since I did not have any balance due to the extension that was approved the {$200.00} payment that I made went towards the fees. I explained it to him that was not what their employee explained to me. Have I known that the {$200.00} went towards other fees I would have made other payment? I was unaware of any past due balance on my account until my credit monitoring service sent me an alert. I asked XXXX to correct their mistake and apply the {$200.00} towards the payment of the loan as it should have been in the first place. Based on the discussion I had with their employee on XX/XX/XXXX and the confirmation statement she read to me, nothing stated that the {$200.00} payment I made went towards fee. She advised me the {$200.00} was going towards the payment for XX/XX/XXXX and she placed an extension request on the account and the next due date was XX/XX/XXXX. 
This company refused to admit their error and on top of it is penalizing me for something I didnt do, I lost more than 40 points on my credit because of the incorrect late payment they reported, and I lost the purchase of my home because of them wrongfully reporting negative information to the credit bureau. 
I need XXXX XXXX to own their mistake and correct their action, and also to remove the incorrect report made to the credit bureau.