I have the same situation with "free care" for indigents. I have saved all of my bills, and can't affoard to pay them either. What I found out, as an example, is that x-rays are covered, but the reading of the x-rays aren't.
The reading is about $25.00 per x-ray. I cannot affoard to pay it, and eventually, they stop sending bills and write it off as a loss. I would still keep the bills, but no repeat bills, just the originals. KWIM? As far as collection agency bills are concerned, just keep one, and toss the rest, also. Once it is written off, you can toss everything. Hope this helps!