Free Movies with On Demand But Now Cost?

When we signed up about a month ago, we were told the movies On Demand were free. The other night my husband watched an old western for free but last night another old western was only for rent or for purchase.  What happened?  When did the free movies (even really old ones) start costing?   Or is there something I need to do (other than unplug my box for Directv and plug it again after a while which is what the guy at the AT&T store said to do)?  As a baby boomer I'm constantly challenged by so-called smart appliances so I need help.  Thanks!