Bad quality DVR issues

My recording keeps starting and stopping, it takes a few seconds for things to fast forward. It has stoped shows saying I’m done when I just started it. Volume disappears in some of the shows. I have also noticed ,some of the shows are very blurry but then come into focus after a few minutes. Also, while taping it tapes the wrong show at the wrong time even though it tapes the same one every day. This is quite annoying.  Can anyone help in what to do?  I have unplugged and reconnected everything.