I used to have a US account on my PAL console due to having moved there to live there for a few years. As such, I downloaded all kinds of DLC for my PAL games (US NTSC games didn't work) and never had a problem with any of it.
Sometimes I could not Download a full game because it was NTSC coded, but the Console always, ALWAYS told me that the game I wanted to buy was not compatible with my console and I hadn't been charged.
In July I bought two Dishonored DLCs, Knife of Dunwall and Dunwall City Trials. I paid for those, downloaded them, but never had a chance to play it. Then I moved back to Germany, migrated my Xbox profile to Germany. Just today, I installed Dishonored again to the HDD and tried to play the DLCs for the first time, and I get the dreaded "The Disc is unreadable - clean it with a soft cloth" Error and get booted to the Dashboard. The Disc. With DLC.
So I did the usual, cleared cache, reinstalled game, nothing.
Then I tried to re-download the DLC... and couldn't.
I am now on the German Xbox Live (and thank you for forcing us to suffer through a German Dashboard translated by Google Translate), and apparently, the DLC is different or something, because it asked me to pay for it again. I checked my download history, and it showed both purchases, but when I try to access the DLC through the Download History I get an Error: "There was a problem with the Xbox Service, try again later, Error Code 800700E8"
On the off-chance, I tried using another US account from my partner that's still US, but to no avail. The same thing happened (Disc Read Error).
So I checked online, on Xbox.com, checked my download history there, and both are there - but again, when I try to click on them, or add them to my Download Queue I get an error, this time: "Unfortunately, the Content is not available"
Finally, I deleted my profile from the console, downloaded it, tried to access the DLCs through my Download History again, and it's still the same problem. I can't use the DLC, and I can't download it again from the Download History or from Xbox.com, and going to it on the Marketplace, it wants me to pay the money I already paid for it - my purchase history is proof of that.
I finally found some info on the web, on this forum, where it says that if you downloaded the DLCs with a US account on a PAL console, you got the NTSC version and that wouldn't work: http://forums.xbox.com/xbox_forums/xbox_support/f/8/p/758385/2988639.aspx#2988639 - and that since the US and PAL version are different (not by content, just out of spite), you having downloaded the US version (that won't work on your console and that you shouldn't have been allowed to download at all) would NOT allow you to delete that and (after migrating to a PAL country) download the PAL version again.
So I contacted MS support, who were less than helpful, basically telling me that some licenses get lost in migration. To the fact that I never could've played the NTSC DLC on my PAL console and that they sold me content I could never have used, they remained silent. No reimbursement, no unlocking the PAL DLC.
I have paid for this, I have proof of that. The content is identical except for the PAL version featuring support for more languages, it was bought at the same price than the PAL content was sold, and it does not violate any German censorship laws.
Suffice to say, I am not amused.