Who Would Ever Believe a Skilled Nursing Facility Would Bill the Patient Co-Pay for Days He Was In Another Hospital and Rehab?

Oddly, we can see here an Invoice from Golden Living Oak Hill including dates when the patient was actually in Beth Israel Deaconess Jordan Hospital beginning 6 July 2015, then Reliant (Spaulding Rehabilitation) beginning 15 July 2015. I actually spoke with the billing people on the phone and they insist there's nothing wrong with the bill. They said the patient had used up all his days for the benefit period and he has to pay. Really? For days when he was elsewhere? How does that work?