Product: Student loan

My student loan is in default and my wages were garnished from XX/XX/XXXX through XX/XX/XXXX without pause.The total amount paid through the garnishments is in excess of {$30000.00}. In XX/XX/XXXX my tax refunds of approx. {$3000.00} were also offset. My original loan amount was approx. {$16000.00} when the garnishment first went into effect. The interest rate was less than 7 % and the statements of interest paid for tax return purposes I have intermittently received ( after many phone calls ) consistently show very low amounts of interest paid. This makes sense if the principal is being reduced accordingly. I have been through XXXX or XXXX loan servicers during this process, the current being GC Services and XXXX prior to them. With both companies I have repeatedly requested a statement showing balance, activity, fees, payments and how the payments were applied. I have never received anything. EVER. My address has not changed, my employer was the same for over a dozen years, yet I get no response. I have no idea how they arrive at the current balance which they still show in excess of {$7000.00}. I have never been offered or been told of any eligibility for any type of repayment plan and was told that I would have to submit all sorts of income and wage verifications prior to receiving any information at all, including a statement! 
Now I am XXXX and have a social security XXXX claim pending. During the last conversation I had with GC Services I was told that if the Social Security XXXX was approved then the balance of my loan would be forgiven, but did not receive any information as to how to accomplish this, no forms to complete, etc. I can not file for XXXX forgiveness until I receive my determination from Social Security, yet should I be entitled to a lump sum back payment I do not want it to be offset to this loan as I do not believe they are entitled to it. 
I still do not comprehend how after repaying in excess of {$33000.00} over thirteen years a {$16000.00} loan amount can still have over {$7000.00} outstanding. I have no idea how I am supposed to deal in good faith with companies that will not send me a complete history of account activity. I have no way to know how much in additional fees have been tacked on to the loan, what interest rate I am being charged nor how the payments have been applied and in what order. In past conversations I advised the companies that I would not furnish any more of my personal or financial information without a complete loan history and I would not make additional payments as they were already garnishing my wages to the maximum amounts the law allows. I am at a loss as to how to obtain the loan history information and there are no breakdowns of fees on the student loan website, only balance information. I can not imagine having to recover funds from this company should they take any in error and wish to avoid this scenario. I have consistently been treated as if I have no right to the information I have been asking for and frankly, find this very disturbing as well as unethical. Any help would be greatly appreciated and I would ask for any responses from the company to be in written form and mailed to my address as I have little faith in telephone conversations with them at this point.