Legal Advice On An Employer Who Overpaid And It Isn't My Fault.

I'm gonna try to make this short but there are a lot of moving parts. I was in a wreck at work. A trash truck ran a red light and nailed me. A little while later I had went on FMLA(Family Medical Leave). While I was on leave after my shoulder surgery. I began to recieve my pay. I would get my pay from my job and then a check from Workmans Comp. Eventually, I got a very small check was alarmed. I called the payroll dept. I was told that I should have only gotten pay from Workmans Comp. They then did some calculations and decided that I owe them roughly 6,900 dollars. I was blown away. Then I got a letter saying that I owed them around 1k a month for my insurance. I felt as if things were going my way with this situation and then all of a sudden. I as the victim got stiffed. I don't have the money to pay any of this. Is there anything to do. This was not my fault in any way. I have never been in this situation at all. I do have a lawyer for the accident and for the workman's comp case. Can I fight this at all. The truth is. It is a shit company and I really watch my back there because I love being an operator. It just seems that since I started there is always something going on. I won't name the company but it is a state job. I work for my local city. Thanks in advance for any advice.