I ve always put up posters on telephone pole in my delivery radius that make outragous claims against them. Like, “Dominos uses rat droppings for meatballs” another idea i read about is starting a website papajohnsrippedmeoff .com or something like that. on the site you can detail how they screwed you on an order or something. The site address can easily be put on an inexpensive bumper sticker.
Even more importantly is that we must answer to the marketplace for our actions. It takes one customer finding out we did something that uncouth, and we loose credibility and loyalty in our market . . . even with ZERO other pizza places. I don’t toy with a reputation as upstanding and having integrity. Not gonna do it.