Product: Student loan

I have private student loans owned by Discover that are serviced by XXXX XXXX. There are two separate, but I think related, serious issues with my Discover Loans : 1. Statements do not make any sense : All of the loans are set up for auto-pay. I received a call on XX/XX/XXXX, just as I am about to board a flight. I was told that for the past several months, I have been paying late, and that I owe over {$200.00}, and would I like to make a payment. I explained to them that was impossible, as the loans are set up for auto-pay. They then tell me I have been paying less for several months then what was owed. They say that my payment went up suddenly a few months ago. I go back to look at the statements, signing into my account, which I had not done in ages, as the payments are all set up to occur on their own / my secretary manages payments for me. The statements make no sense, they state I overpaid for several months, XX/XX/XXXX, XX/XX/XXXX, and several others. Despite these " over-payments, '' they claim I still owed money and had not paid my full amount, which makes no sense. I asked to speak with a supervisor, and I was transferred. I spoke with XXXX at Discover, ID XXXX. XXXX was fantastic. He immediately pulled up my statements and said he too could not make heads or tails about what happened. He said none of the payment info made sense, there was no indication as to why my payment went up by nearly {$200.00} nearly 6 months ago. XXXX was awesome, he did a weeks worth of research and called me back ( we scheduled a date and time, and he called me exactly on time, it was so professional ). XXXX explained that from Discovers end, they could not figure out what was going on with the statements, and that they made no sense. He said I would have to call XXXX XXXX. I let XXXX know that in between our calls, I had already called XXXX XXXX, and they said they were unsure and that it was a matter to take up with Discover, as they own the loan, and XXXX XXXX is just the servicer. XXXX was upset by this and committed to looking into the matter. 
2. Error and items missing from the original master promissory notes : when I started looking closer at my loans, I realized some of the interest rates had margins much higher than I ever remembered signing. I raised this issue to Discover, and they told me the margin can be found in my master promissory note. I downloaded my MPNs and read them cover to cover. The promissory notes state : The interest rate during the Deferred Phase and the Repayment Phase is calculated as the Prime Index plus the " Margin '' percentage identified on my Disclosure Statement ( which is incorporated into this Note ), yet, no disclosure statement is incorporated into the promissory note. At no place in the note does it list what the margin is on each of the 3 loans. I Raised this issue to XXXX, and after researching it, he confirmed that the notes I signed do not list the margin and do not have a disclosure document incorporated into the note as the note states. He said from his end, there is nothing that could be done about this, and said I would likely need a lawyer if I wanted to proceed. I explained to XXXX that this is very concerning, as there is no proof that the interest rates they are charging me are what I agreed to nearly 10 years ago - since the legal binding document has clear and obvious errors. 
Aside from the SERIOUS issues regarding the errors in the promissory notes, which are what determine the very foundation of these loans, the fact that Discover states theyve researched my statements extensively and cant understand them is even more troubling.