Got two letters that totalled about $3k in debts... (I think I was pretty early in the whole process.)
I knew that I had always reported as accurately as I could so was pretty confident that I didn't owe anything (or at least not anything close to that much!)
When the debt collectors called my stress levels went right up! I managed to pretty much hold them at bay (I think I only agreed to them taking $20/month - though I wish I'd gone for $1) while I was trying to gather my proof.
In the end I think I paid about $300 after submitting my evidence and having it reviewed.
This is criminal.
The algorithm has been shown to be faulty and yet they persist with hassling and harassing some of the worst off in the community!
And they set up a very difficult process to do anything about it when you're selected.