I think I posted arlier in this tread.
I would go to dealer and ask to talk to service director. Be polite and calm. Explain where the rust is on the car. Tell him how disappointed you are to have such a rusting problem and that otherwise you like the car. Tell him that you have heard good things about how Mazda has stood behind their product and is fixing the rust for their customers.
I have had success getting my 2005 repaired in 2009 and also arrange for the repair of my friend's 2006.
The key is talk to service director as many of front line staff may try and brush you off. Stay calm and polite. Make them want to help you. Try and give the impression you really like Mazda products except for the rusting issue.
Good luck
All very good advice. It's all in the approach. Treat the dealership with respect (at least initially!) and they will often reciprocate.