We have a similar problem, but not with misguided bill collectors, it's with job recruiters. Evidently, "Phyllis" and "Julio" added their names in some kind of nursing job database about a decade ago....and then we acquired their phone number when we moved in 2006. We're constantly getting calls for them about job opportunities.
We used to ask people to remove their names from their database, but that didn't work. Now we're telling people they're dead, however that doesn't seem to be working either.