I may be the last person in the universe to hear about the prank the Deutch comedians with a cause played on the communications firm Mobistar.
If you don't know what I'm talking about, Mobistar has a fantastically bad reputation for customer service. These people put themselves inside a shipping container and had it delivered to Mobistar headquarters and placed compeltely obstructing their front entrance. They put their "Customer Service" number on the outside, and the comedy started there.
The State We're In interviewed the pranksters here:
http://www.rnw.nl/english/radioshow/unmasked. Also, they talk about pranking a spammer...