Violence might not be a solution

But boy wouldn't it be nice to just use well-targeted (or messy, at this point, I can't say I'm fussed) violence every now and again, just to teach those cretins a lesson?
I went to the post-office today. Yes, my life is thrilling, whatever. We'll talk about my life, or lack thereof, some other time, shall we?
I had been waiting for two books for ever, and they finally got here today. Actually the postman or delivery person or whatever they're called for this kind of trackable parcel service was apparently round to my flat twice and I wasn't there twice. In the morning. I wasn't working this week. I was hungover yesterday. I would have heard the bell as loudly as if it'd been rung inside of my own head. Who the... hell... does he think he's kidding?
So off I went to the post-office, armed with patience (don't know if it's a phrase in English, but it is in French, and boy does it ever apply), and was annoyed from the onset to see that three people were manning the desks, or, again, whatever they're called, for a 25 strong queue.
I'm incensed all over again now. Which explains the definite hint of aphasia. I can feel my blood bubbling, the voices inside my head have gone quiet, and my fingertips are tingling. Bear with me. Or don't, actually, that's the beauty of the internet, isn't it. You don't, in fact, have to hear this out.
OK, where was I? Oh yes. The post-office. The queue. The 3 people for the entire queue.
Well, let's just say sometimes I'm grateful I never did any martial arts or gun-training. And leave it at that.

But they'll pay one day. Surely. Karmic retribution or something equally painful. And I'll laugh that day. I will be there and I will be laughing. I'll wave the two paperbacks that I queued for for half an hour and had been waiting for for two months, I'll wave the CD that she sent me and took a month and a half to arrive from the US, I'll wave the printer that I had to wait in line for for god knows how long, I'll wave the photos, the DVDs, the registered mail, I'll just wave it all and cackle wildly!
And then they'll shoot me up with some kind of sedative and I'll be happy again.

Oh, but I still have to think of the punishment they'll be going through while I cackle. Suggestions?
Anyone? Anyone? Something d-o-o...?