Issue Downloading Citadel DLC on PC

I ran into a rather odd issue after purchasing the Citadel DLC for Mass Effect 3 on my PC; the download will get to about 3000-3200 MB, then reset to around 1800 MB - EVERY TIME. It's been doing this for over a week. I have plenty of space on my HD (129 GB free on a 200 GB drive) and the HD is not failing (I not long ago switched to this HD with a new installation of windows because a different HD was too small - this one's been tested thoroughly).

NE 1 have NE ideas why this might be happening? It's maddenning and I'm on a shared internet connection - I can't keep downloading because it's not fair to take up so much bandwidth all the time.

HELP HELP HELP!!! :P

Thank you for your attention.