Complaint sub-issue: Account status incorrect

I am the co-signer of student loans payable to American Education Services ( AES ) of XXXX, PA for both of my XXXX  daughters. They graduated from college from XXXX in XX/XX/XXXX, and, soon afterward, I began helping them make payments or actually making payments on their behalf as they tried to establish themselves in their new careers, housing, family situations, etc. 

For a long period of time, I had been sending in payments to AES on one of my daughter 's loans identifying the payments under her account number only. Unbeknownst to me, however, AES apparently accounted for the loans under both an account number for her as the borrower and another, different account number for me as the co-signer. Nevertheless, this situation continued for quite some time with no significant problems noted until AES sold off all of my daughter 's loans to another entity, retaining only one loan of my daughter 's. 

AES never communicated this change to my daughter or myself, and I only discovered the change when the other entity ( XXXX ) began  communicating with us and sending monthly statements. Receiving monthly statements was new and totally different concept since AES never sent out monthly statements, and I essentially had to keep track of payment amounts and due dates on my own. 

Soon after the transition to XXXX, I began receiving late payment notices from AES though, and, when I called them, I was informed by their telephone representative that AES had retained one loan and was told the monthly payment amount and due date. Thereafter, I faithfully made the one monthly payment to AES using my daughter 's account number ; however, I continued to receive past-due letters from AES. After checking into it further ( by calling AES several times ), I found out that I had a separate co-signer account number with AES, different from my daughter 's number, and that my payments over the last 4-5 months had been posted to her account number instead of my co-signer number. 

About this time, AES made a negative credit report on my account/Social Security or ID number. The AES telephone representative assured me, though, that this matter could be cleared up if I faxed AES proof via bank statements, canceled checks, etc. showing that the payments had been made by myself and requesting that they re-apply the payments in question from my daughter 's account number to my co-signer number. I did this on 3 different occasions over the course of approximately 2 weeks, with the first fax being done in late XX/XX/XXXX and the third done on XX/XX/XXXX. 

AES claimed they never received the first fax in XXXX, and I was trusting enough, at that time, not to keep a copy for my records. The second fax was done on XX/XX/XXXX, which AES later told me was sent to an incorrect fax number of theirs although I faxed it using a number they had provided. The third fax, which I believe they did in fact receive, was on XX/XX/XXXX. 

Meanwhile, my wife and I are in the process of applying for and obtaining a new home mortgage, and AES 's incorrect credit report on my ID is causing us significant problems in qualifying for the credit due to my artificially lower credit score. Please help!!