What should I do?

I had a $50,000 overpayment applied to my student loans because I was accepted into a loan forgiveness program that my state was offering. I was able to specify which loans I would like the overpayment applied to. However, Mohela applied the $50,000 to my loans that accrue the least amount of interest, as well as a grad plus loan that was only about $8,000 in total. The grad plus loan is now showing as -$28,000. Why would they apply $20,000 to a loan that only had $8000 due? Anyway, I had made it clear which specific loans I wanted the $50,000 to go toward and how much of the $50,000 to put toward each loan. (I want the money to go toward the loans that have the highest interest.) I have my first payment coming up in June. I have emailed Mohela numerous times dating back to early April and seem to just be getting AI responses. They first told me that the situation would take 2-4 business days to be corrected. Now, they are telling me it will take 90-120 days to be corrected. I don't even know what to do…Are they really expecting me to make a payment on loans that should be paid off? This is also making my payment higher because of the amount applied to my grad plus loan which is now showing as a negative balance. I am so frustrated