I worry about the feedback loop here. You stopped going because of the ads, but unless the person making the decisions knows that, then these things don't change. I don't have a solution.
I don't really care though. Gas quality is the same across brands.
The second time we didn't go there while passing that place, I dropped them a friendly mail. I must have been not the only one, because now they accept cards.
Sometimes talking to people helps. Though with a franchise there might be no-one on site with the power to "just fix" things. Regarding the gas station: Maybe charge at home instead? :P