It might have to do with the region of the client versus the region you're playing the game in. For example, I play in US and after going through the same problem with the patch update multiple patches in a row now, I've just realized that my game client is Europe. Somehow I live in Australia, play on the US, I'm regionally closest to Asia, and have a European client.
So I uninstalled and I'm re-downloading the client. We'll see how it goes...
So I re-downloaded the client by going to my account on Blizzard's page, and again my client was European so I guess I somehow bought a Euro collector's edition. I then uninstalled the client again and downloaded the US client by googling "diablo 3 US client" and it works.
Cant say ive had any problems with the patch days my self....
So I uninstalled and I'm re-downloading the client. We'll see how it goes...