That's what I wrote to support group:

Todays 4.3.2 patch is really problematic.
1. One of GM's replies said it's just ~2mb patch, while my downloader wants to download more than 6 gb of data. Hard situation, especially when I have only 20 gb available per month.
2. Game is though "playable", but when WoW starts in the left bottom corner there's US ESRB notification instead of EU PEGI, and when I try to log in it says that I haven't WoW attached to my account. Just yesterday I've played EU version and next day it's US?
I need some explaination and help if it's possible.

And that's the reply I've received:

Greetings,

Unfortunately your game patched to wrong region version. You would need to fully uninstall the game through add remove programs and remove any remaining files. Please then install the game from our online game client making sure your installation is in correct region: https://eu.battle.net/account/download/

If one of your friends has game installed and patched on their PC, you will be able to copy installation files to your hard drive without online installation.

If you have any additional questions or concerns, please reply to this ticket and we'll get back to you as soon as possible.

Isn't there really any other way out?
And how the hell could it happen that yesterday I played some bg's on EU realms and then another day patch "fixes it" to US version? It was all downloaded and updated by launcher, not manually.
I've used my whole download limit for this month just to know that I need to reinstall it and download another like 10GB of patches because none of my friends play WoW. And game time ain't gonna stop.