Student Loan Rehab Default

I have a federal student loan of almost $7000, now through NCO Financial. I called NCO to set up a payment arrangement and they told me my best bet would be to go through the rehabiliation program. I agreed with that, but then I was told that I was not in fact eligible to rehabilitate because I had previously defaulted on a rehabilitation program. Instead, they want me to pay the full amount or make a settlement of about $5000. However, I know I have never defaulted on a rehab program. When I asked NCO for details of the default, they referred me to the Department of Education. For 3 weeks I have been passed back and forth from NCO and DoE, with no one seemingly able to help me. I have talked to supervisors and floor managers and even the "vice-president" of NCO (yet strangely even he could not help me). The bottom line is: NCO is not able to provide any proof that I defaulted on the rehab program. My name came over on a list of defaults from the DoE. The DoE claims to know nothing of this supposed list and from their information, there is no reason why I am not eligible to rehabilitate. NCO claims that because my name is on the list, they cannot help me. Both the DoE and NCO have assured me that my dispute has been "escalated" and presumably being looked at by the higher-ups, but at this point I no longer believe anything they tell me. I am so frustrated with this process and I feel like NCO especially is just trying to wear me down so I pay the loan off and move on (and I probably would if I could).
I need to know what my options are at this point. I want to get into the rehab program so I will be eligible for student loans again. I have so many complaints about the way I have been treated, but if I could just get some resolution regarding my eligibility to rehab, I would chalk this up to a learning experience and move on with my life. Anyone have any suggestions as to what my next steps should be?