The most straightforward reading of this, which is that they had her contact information but spoke to family members anyway, is a pretty clear violation of the Fair Debt Collection Practices Act. Leaving twenty messages per day is also a violation, though debtors have been known to ahem exaggerate that one.
That they used Facebook is irrelevant -- calling the sister, emailing the sister, or sending the sister messages via carrier pigeons are all equally illegal. And if they were stupid enough to post a message on her wall about it, which I doubt, statutory damages would hit six figures very, very quickly. ($1,000 for every Facebook friend who is not your spouse.)
That they used Facebook is irrelevant -- calling the sister, emailing the sister, or sending the sister messages via carrier pigeons are all equally illegal. And if they were stupid enough to post a message on her wall about it, which I doubt, statutory damages would hit six figures very, very quickly. ($1,000 for every Facebook friend who is not your spouse.)