3 times in a run is impressive. Doesn't beat my record of 7, but in current activity scales its pretty good. From my point of view, if your ore run is selling for 50 million, then the max that any one pirate can ask of you is 50 million. If you're buying it from a PoB, take into account those prices, and adjust your run, or buy-point accordingly. Maybe get a friend to mine the ores so that you have total buypoint loss of 0, or invest in defense contracts with bounty hunters and freelancers. Or, my favorite solution, play a Junker and only trade across Bretonia-Rheinland-Omegas-Omicrons so that you have a grand total of 0 enemies.
Pirates demanding more than your total Ore sell price is a rule violation for sure, but there's an even easier answer when that happens: Just don't pay them. The best they can do is kill you, take the ore, and sell it at a fence point for a grand total of way less than they were trying to get from you. Get a miner who'll mine for free, and you only lose time, metaphysically cucking the pirates directly in the ego. The chaddest move.