They weren't tasked with working on the exhaust, they replaced a fuel pump and had ZERO issue with doing so. Sorry, but I just don't know what you're on about or why you're so bent out of shape. Speeding is a crime, talking on your phone while driving is a crime, does that mean jails are full of speeders and cell phone users?
It doesn't mean that a dealership tech is somehow going to lose their certification for doing warranty work on unrelated items if your car is not street legal. Now if you asked them to remove your catalytic converter clearly your request would be denied.
Sorry you're so worked up, but cursing and insulting somebody directly really isn't called for here.
As always, you can believe what you want to believe. Nobody is going to tell you differently, and I for one, really don't care what you do/don't believe. Trying to please every person on a forum ended about the time I turned 25. And that was over a decade ago now. But you CAN grow up and cut out the cursing and direct insults.
I am 50. I have been a mechanic both private and for dealers for the last 30 years. So I have just a touch of real world experience with people storming into my shop/dealership with threats of lawyers and suing and such. 90%+ of people like that just get ignored for one. Secondly, the other 10% tend to get escorted out by police. IN the end, maybe, just maybe 5% actually get something out of the dealership. THe vast majority are soundly ignored.
Telling people to walk into a dealership and start threatening then with legal stuff is HORRIBLE ADVICE. You will get ignored. I guess you have that one dealership that is willing to work on your illegally modified cars, but I can tell you we take cars like that off the lift before turning a single wrench. It is something called liability. No mechanic/dealer in their right mind is going to help you and chance losing their license and franchise. If they actually did, good for you. I do not believe you.
Modifying a car under manufacturer's warranty will void the warranty on the systems you modified. If you modify exhaust at any point, it voids all warranty on the exhaust system, emissions controls and even the engine. I am sure you will say I am wrong, but have you ever even looked what they write on the warranty disclaimers? I can't believe you have.
As I said, this thread is going nowhere because the advice is now on the level of foolishness. The only step now is to call Mazda corporate and see if they will offer anything. You can threaten them as well, but unless you actually spend the money and file an actual lawsuit they will laugh at you. As for Facebook, that is even more laughable.
Complaining that you are being denied warranty service on a car when you modified it means you never read the terms of your warranty. The dealer gets to decide what they think could have voided it, which they all seem to do 99% of the time, and once it is reported on the dealer's computer your car was modified, it will be in all Mazda dealer's computer when they type in your VIN number. You're pretty much done, if you pin your hopes on that foolish Magnuson act then you need to get a lawyer and file a lawsuit.
I have yet to meet a dealership manager or service writer that even flinches when customers come back threatening with lawsuits. In fact, most small car lot dealers will likely physically toss you off their lots. The franchises will just call the cops and have you removed.
OP, report back with what happens if/when you demand the dealer do something. Don't listen to any of our advice, listen to what Mazda Corporate tells you. Dealers do not deny warranty claims. They submit estimates to Mazda for approval. Obviously, they try to save corporate money by looking for things that can assist them in denying claims. Mazda is your only hope.