DVR incomplete recordings

I am attempting to watch several programs which I recorded 3-6 weeks ago.  About 1/3 of them run for 3-20 minutes (into a 60 minute program) and quit.  The display show them as 100% "watched".  Restart goes no further.  I pay extra for extended DVR capacity, an apparent waste of money.  The AI assistant is no help, and I cannot find a way to reach a human being.