Wiring problems of the 2005 Mazda MAZDA6

I purchased a new Mazda 6 in 2005. Since then I have had to replace the battery 3 times. Each time the battery went out with no warning. It would be driving fine, I would park and get out. When returning to the car, it will not turn at all. Internal and external lights and radio worked fine but car will not turn. The first two times the battery was jumped and the car was taken to a Mazda dealership and replaced under the Mazda battery manufacturer warranty because they went out before the 36 month warranty. The last time in August of 2010, the battery will not jump. I paid to have the car towed to a Mazda dealership. I was told that the battery had a crack in it and acid leaked out and as a result, the engine wiring harness needed to be replaced. At this time, the battery was covered under the Mazda manufacturer warranty and the wiring harness was covered under my Mazda extended warranty plan. I did some research and found that there is a possibility that the leaking acid could have caused an explosion and my family was lucky. I received a call from the dealership saying that the manufacturer warranty will replace only the battery itself and the extended warranty is denying the entire claim because the damage to the wiring harness was from the battery acid. So, here I am with a battery under Mazda manufacturer warranty, covered by a Mazda extended warranty plan and I had to pay for everything except for the battery itself. I paid for the tow, the labor and parts for the harness, rental car while it was being services. And the fact is that there was a faulty battery that leaked acid, put my family in danger, and I was stuck with the collateral damages. Considering that this was my 3rd battery replacement in 5 years, I'm certain there is something wrong with these batteries or something in the car itself. I am now driving with my 3rd Mazda battery replacement and afraid of when my next incident is going to be. .