I want to ask your advice on something , I was in a fender bender but it was the other person's fault?

I was in a fender bender but it was the other person’s fault so their insurance was going to pay for the damage. So I take the car to the auto body shop they call the car rental place they come pick me up take me and give me a little crappy car to drive, so that day comes I take the car back they take me to get my car and it’s a done deal a couple months go by I get a letter in the mail from a collection agency telling me that I owe Enterprise for two days rental this is the tricky part the body shop told the insurance company that my car was done two days before I picked it up and they said I picked it up. But my receipt and Enterprises receipts say that I turned it in two days later do you think that enterprise since they’re the ones that sent it to collections should notice that the receipts say I turned it in two days later and said something to the insurance company or do I go to the body shop and tell them to pay for the extra days since they are the ones that were lying and wrote down I picked up my car when I didn’t or should I just pay it myself what would you do ?and are they allowed to charge you after you’ve left and your receipts says paid in full isn’t that illegal?