You are getting calls because this is probably a dishonest or "fake" debt collection agency who uses software (some publicly available) which list all known associates (and ex-spouses and in-laws show up). We have seen these vermin call people regarding ex-spouses from over ten years ago. If my hunch is correct, these are criminals who have no boundaries and respect no laws.
Since debt is a civil and not criminal issue, no one will be arrested ever. Second, if someone is getting "served" they never get the heads up first. Don't sweat it and enjoy your hollidays