CBS All Access charging for shows

We purchased the subscription for CBS All Access through Apple TV. A few weeks ago I was getting caught up on NCIS NOLA and all of the sudden it tried to charge me for a bunch of episodes on this show and several others. After a couple of days it rectified itself. Now It is allowing me to watch a few Magnum PI episodes free, but then charging me $2.99 on many others. Why am I being charged for these episodes if I purchased the app. The last time I contacted CBS directly and they said that since my subscription was through Apple TV I had to contact Apple TV directly.