From the Blizzard Europe website:

In our continued efforts to combat cheating in World of Warcraft, more than 114,000 accounts have been closed across Europe in the month of April for the use of “bot” programs. The banned accounts were taking part in activities that violate the World of Warcraft Terms of Use, specifically, using unauthorised third party programs to automate game-play.
Such behaviour not only negatively impacts the game’s economy, it diminishes the achievements of those who play legitimately.

It is our goal to provide a fair and enjoyable play experience for all World of Warcraft players. To aid us, we ask that you abide by the Terms of Use, which, among other things, provide for the security of your account details, payment methods and login information, all of which can be compromised if you choose to use third-party services or programs.

Over the coming months, we will continue to take an active and aggressive stance against botting, as well as work to resolve other issues such as in-game advertising for the sale of World of Warcraft content and for-pay power-levelling services. Many account closures come as the direct result of tips reported to our GMs in game or emailed to our Hacks Team by legitimate World of Warcraft players, and we thank you for your assistance in preserving the integrity of the game experience.

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Congratulations Blizzard but you ultimately failed people like me who took the time to report these people, we eventually got pissed off, gave up and left.
For every one honest player you must have tens or even hundreds of bots currently in your system.

Instant lock-outs for these people and then investigate please.