November 2013 - last edited November 2013
After trying to get help from EA help chat who told me to manually uninstalling then reinstalling Origin which I do and I still can not get my Mass Effect 3 DLC to install or even download.
I thought I manage download it as that's what Origin was telling but after the download and clicking the ready to install nothing happen so I left it for the night and came back to it this morning to find that it no longer is telling install but download. I click the download button next to the DLC I want and it ask me what language I select English and nothing happens.
When trying to load a saved game I get a msg saying that I'm missing DLC and can't play that saved game therefore the DLC is not installed.
Update a fix can be found here http://answers.ea.com/t5/Mass-Effect-3/ME3-DLC-Downloads-in-Origin-not-working/m-p/1866903#U1866903
(I search for ages and still only found this by luck after post this... you need to improve the search)
To EA this need to be fix when I download ME3 DLC it should go the ME3 DLC folder not to The Final Hours Of Mass Effect 3 DLC Folder.
Being a PC repair tech I feel like throwing in my two cents for schits n giggles:
The answer revolves around the installation folder itself. That's a Windows problem. The administrative rights grant you full access, but when uninstalling a program there are more often than not folders and files left behind. Essentially the problem is eliminating all of the folders/files when uninstalling & reinstalling. The easiest solution would be for EA to offer a 'reinstall' feature for PC users that includes a special command to fully wipe & create new folders.
Ultimately this is a similar problem with other games & antivirus programs in Windows, not specific to ME3.