I have an '01 F150, so you may be in a whole different league than me, but I do all of my own brake work. I just replaced my rear pads and rotors about a week ago, front ones a couple of years ago.
What kind of pads are they using at the dealer? What kind of rotor are they using? If you can find a rotor made in the USA it will cost you more, but it is generally much better steel. Most of the ones being put on these days come from China, and their steel is not as good (generally speaking), meaning more prone to warping under somewhat normal conditions. Their heat treating processes and grades of steel are inferior. I wouldn't be surprised if this warranty work is being done with the cheapest parts they have available - BUT that doesn't explain why it happened with the OEM parts.
The reason I started doing my own brakes is because of stuff like this with "trained professionals." The other thing they do is crank the crap out of your lug nuts. On my last truck I had to replace FIVE different studs due to the guys at the shop over-torquing them with an impact wrench and then when I'd go to rotate the tires the stud would just break.
Anyway, back to your problem, you might try a different grade of pads. Lots of people use Raybestos, I don't like them. I've had great luck with Weaver Gold - they stop great, don't throw lots of dust, don't eat up rotors, and don't squeak like the ceramics. A change in the pad make might help. They are softer and your pads will wear more, but that's better than your rotor wearing excessively. Also, I NEVER let them turn my rotors. That just makes them thinner, more prone to warp... etc. That's just me - I'm a bit hard headed about that, but I use softer pads so that's not a problem. By the way, the only reason I had to replace the rotors is because I tend to have the music up too loud and don't always hear it when the wear indicators tell me to change them. I went too far and got into the rotor. However, using those softer pads, WHEN I change them at the proper time, I've never turned the rotors and have been through several pair of pads in the 100+K miles on my truck.
I've not seen the slotted or drilled rotors for your size truck, although they may exist. Just make sure the holes are random or they will be loud.
I don't know how much any of that will help, but I would have to agree with the thought of trying a different dealer if you don't want to bother with doing it yourself. And, if you really do have a problem it would probably be good to take it to a brake specialist - Midas for instance. If I thought I had a problem I wouldn't fool around with something as important as brakes. Good luck.
