One thing we did once with a couple of friends is we spent a whole night taking up all the spots at a specific gas station, and doing a "who is able to fill up the least" contest.
It would go like this:
1-Park your car at the pump.
2-Put the least gas in possible.
3-Go in the store and pay by credit card.
4-Repeat, starting at #2, until you are full.
This does 2 things:
-It takes up all of the spots at the gas station for the whole evening, and the station only gets profit from 10-12 fill-ups.
-The gas station pays credit card companies per transaction, so it almost costs them money that day. I know they absorb it with the full month, but it still pisses them off.
Do that at random gas stations every once in a while, and they start to get the message. You can even get yourself on the news that way. You have to be very patient, though.