Download Cata data without Digital pre-order

1) Open up your WTF folder found in your root directory

2) Open Launcher.WTF with a text editor (like Notepad)

3) Change:

SET accountType "LK" to SET accountType "CT" 

4) Open up Config.wtf with a text editor

5) Change:  SET accounttype "LK" to SET accounttype "CT"

6) Start downloading by opening Launcher.exe

If this doesn't work for you, you can download a mirrored version of the files:
expansion3.MPQ - 632.3 Mb
expansion3-speech-enUS.MPQ - 55.5 Mb
expansion3-locale-enUS.MPQ - 1.0 Mb

Enjoy!