I can see how frustrated you are about this.
I was just about to suggest writing a letter but see you've done that. When government is involved there is just so much red tape to make changes.
Maybe an easier route would be, instead of asking the dangerous and offensive material and foods to be removed, request the addition of healthier foods to be included. You probably have to band together with other concerned parents.
One of the ways to completely avoid this is to homeschool your children. Which is what I've done for my kids from the beginning. I have my first high school graduate this year, so I've been doing this for 12 years now. I think homeschooling the early years is the best time, that way if they ever do go back to public school they have a foundation.
Yes, healthier foods has been suggested and I even had plans to get my local organic foods supplier help with the process, but it was turned down due to lack of support...
I wish that homeschooling was an option for us. My wife doesn't have the patience to teach and I work during the day. We do our best to teach lessons above and beyond what the schools teach by taking them to museums, the science center, watching education programs, going through biology books, etc.
It's just so disappointing that kids pick up good or bad habits from an early age and the school seems to be doing everything they can to make sure that kids grow up sick and obese!