good to know - have emailed the collectors and included a link to rightmove that shows the sale of the house and noted that Land Registry's been updated too - so can forward them a copy of the deeds if they really need (but tbh they can buy a copy themselves).
thanks folks - had the meters reset (they were pay as yo go) and since changed to a smart meter, so that side of things was sorted way back when.
will drop the debt collectors an email with a burner account, as i'd rather they didn't have my number.