My father had surgery to drain a very large abscess, which then required 8 weeks of home visits from a certified wound care nurse plus the wearing of a negative pressure vacuum pump. She left a small sponge inside the wound which later caused three new abscesses. This required a trip to the ER, hospital admission, draining, antibiotics, debridement and wound care, and a four night stay in the hospital. He has Medicare which covers 80% of the costs, but there is still a significant amount of money he is expected to pay. How do we contest this?