I think your husband should go back and tell his employer that because they've been doing it for the last x years, it has become an implied term and condition of his employment and they can't just go changing it willy-nilly. As an absolute minimum they need to give him his contractual notice period (basically one weeks notice for each completed year of employment, minimum one one, maximum of 12)
Changes to T&Cs should be put in writing to each employee - so don't let get away with any old bull about 'oh, we told everyone last month about it. Poor management indeed.