Med rep needs advice!

I am a med rep in central Nebraska. My main account is a CHI facility. Over the past few years the situation reguarding their sterile processing department has always been the same. That being that the surgical tools and trays owned by the hospital are the hospitals responsibility. They are responsible for washing, setting, and sterilizing said trays. We as reps always take care of our trays that are at the hospital, but the hospital does not own. I am told it is this way because of liability issues where the hospital cannot put the liability of their owned trays on the rep or company, and the reps or companies cannot put the liability on the hospital for trays they do not own. CHI has cut almost half of their sterile processing staff at this location, claiming they were overstaffed. As a result, the hospital is now telling us that we have the liability for all trays and tools hospital owned or otherwise. We are a very busy account and are in the OR doing our jobs for about 10hrs each day. Now, the hospital is saying we are basically required to stay and wash and set trays. Or at the very least set the trays. The issue is it takes 4hrs and sometimes more to get our trays through the washer so that we can set them. I have been at this hospital untill midnight or later in several occasions to set these trays....after a 10hr work day. The hospital is basically saying that if we as company representatives want to keep our customers (the surgeons) happy, that we have to do this. We are NOT in anyway employed by the hospital. We are however either salaried or commissioned by our company. At the very least I figured this constituted some sort of slavery or non-pay violation by the hospital as we are doing their work for no pay. Also the hours that are requested of us are staggering. I've brought this up with our companies management and have thus far made little progress. I was hoping someone could tell me if in fact the hospital is violating some form of labor law? Any help would be appreciated. If not, I will definitely need to seek other employment as I cannot keep up these hours. Not to mention this is 1 of 3 accounts I am supposed to cover. Neededles to say my other accounts have seen very little of me, if at all.