The first thing to pull out is your
cellphone, dialing 911. Report an altercation at XYZ Mart at the corner of Whatever and WhereamI. The Pump Nazis may decide at that point to flip you off and let it go.
If necessary, pull out your pepper spray. You're not going to jail for having that in your hand. But as you reported it, this is just not a "I needed a gun" moment. (But you should have had it on you anyway, just because.)
You did fine, although the "none of your business" comment probably escalated it and you might have done better saying nothing at all. I had an unexpected altercation myself recently at the Home Depot. It was raining, I have arthritis, I was hurting, and I needed a close-in spot. I pulled up to the DP spots near the entrance, and some nitwit had TWO trucks (yes, you read that right), his pickup and another, plus a CAR, taking up three or four of the DP spots on one side. I pulled up and stopped, trying to figure out if I was really seeing what I was seeing...these geniuses were loading up one pickup truck and apparently were also dividing their purchases up among the other vehicles. None of the vehicles had a handicapped plaquard or license plate. I backed up, scooted the car around and got into one an aisle over; and as I went past them going in, I said, politely, "You know, that's for DP plates only".
The guy went ballistic. He followed me across the parking lot screaming about how many DP spots Home Depot has. I was not worried about a physical assault; he just felt like he had to reassert his alphadom, such as it was. I went into the store, and checked to make sure he didn't follow me in, or go back and damage my car, and let it go. During his rant, I just kept walking and didn't answer. Anything I could have said would just have made it worse, and there's not much less dignified than a 52 year old woman in a shouting match with a fool.
You and your dad are okay, but I would seriously recommend thinking cellphone and pepper spray first in some sort of loony problem like this. (And others are right...there is no such thing as a "passenger side pump". That's just goofy.
Springmom