Finally, I got the "nice space station you got there, shame if it should get blown up" message.
In EVE hi sec, within the territories of the big NPC empires, there are police. However a contribution to their benevolent fund will cause them to turn blind eyes to shenanigans. These are called WarDecs.
The rules for blowing up space stations are intended to prevent Corporations in different time zones from making surprise attacks when the other guys are fast asleep. First, attackers have to knock down the station's Shields. A week later, they can come back to destroy its Armour. Finally after another week, and that was today, they can destroy it.
Now my corporation specialises in arms dealing not combat, we are small, defenceless but wealthy so we hired mercenaries to defend us and the extortionists backed off without a fight. Hopefully they won't try that again, it cost them money and a complementary Bounty on their heads. It cost us a few million ISK as well, mostly in lost production, but we can make that up in a few days.