Repossesion legalities?

My Fiance and I bought a used truck about 10 months ago. It's seems like shortly after we bought the car, we started having financial issues. Any how, now we are having a lot of trouble even making partial payments. Our payments are 331.00/month. I spoke to our finance company this morning and tried to ask if they could please work with us, and let us pay them what we could now, and later, give them more until we are caught up. However, the customer service rep said that the minimum payment they can accept is 255.00. With the 1st around the corner and other bills at stake, it's hard to make that commitment. So my question is.. If I were to shoot them lets say 100.00 dollars, could they still take the car, because technically I am still paying on it? Or what are the legalities? Is there something I can do, in which they would have to cancel the order for repossession?