Keep in mind we are just users like you in these forums.
I too had this problem a few months back. I tried all the same things you have done and even had support place copies of the same show over and over again in my downloads with no luck.
I kept trying over and over again and one day the download was successful and I didn't have to do a thing. It just worked.
I realize that this is a "user" forum per se, but I figure somebody from Apple might peruse by here or somebody with my issue, such as yourself, might have some suggestions.
That being said, thanks for the advice. I can't help but keep trying because everytime I open Itunes, it tries to download the episode, and I get the message within a minute or two of opening Itunes. It also will download other subscription TV shows that I have bought just fine, no problems. I guess that is what is so frustrating. This has happened to me before and I had to download it from another computer, put it on a memory stick, and bring it over, but that is such a pain to do, and you would think that SOMEBODY at Apple realizes this is going on (since the Google search I did was plastered with all kinds of similar issues) but it seems to me that Apple is starting to get "Microsoft disease". I used to work over there, and they have so much money, they pretty much could care less about their customer service. I was there when they SHOVED WindowsME out the door, even though it had more bugs than a Tiajuana whore house, and they KNEW it but forced us all to sign off on it (I was in USB testing at that time), and I would never put that operating system on any machine I owned. I think they pretty much took that attitude with Vista too (I wasn't there), and it got such a bad name, they came out with Windows 7 which is basically Vista with the bugs fixed and the graphics are a little better.
I will keep trying I guess...what else can I do?
I'm having the exact same problem once again myself. Today I bought all four seasons of Parks and Recreation since they are on sale.
I'm downloading seaso three now and one of the episodes suddenly gave me this error. As before back in February when I last experienced this problem, it gets to 10MB downloaded and starts over. It tries again three more times then gives the error. As before, I then try to download on my iPhone. The file gets to 100%, shows processing file and then starts all over again.
I got my two episodes to download completely by tethering my iPhone to my Mac.
I started my phone as a hotspot, turned off my WiFi on my Mac and then opened iTunes so that the two episodes would start downloading that would not download using my WiFi.
Once each episode got to 12MB downloaded, I stoped each one and then disconected my iPhone. I turned on the WiFi on the Mac and the in iTunes hit the resume downloads button. Both episodes finished completly. Using my WiFi, the downloads would fail at 10MB downloaded which is why I waited till each download got to 12MB before stopping.
Well, I waited and waited, and just woke up after leaving Itunes on all night, and the file somehow got downloaded, and it's on my hard drive now, no more error messages after all the futile failed attempts. I wonder if Apple just occasionally sends out corrupt files, then fixes them after getting complaints, who knows. It's still a pain in the rear.