Filling up with unrequested recordings

Is there a way to stop my DVR from recording shows that I didn't request? It's filled up a couple of times, and it's super annoying to miss a recording because of a DVR full of random stuff I didn't request? I couldn't find a feature/option anywhere to shut off/disable.  When I search the forum I think kI see others have had this problem also, but don't see a solution other than to "open a ticket", which doesn't make sense.