Plugging the gap

I'VE HAD to replace two welch plugs in my 2002 Ford Falcon Forte that had done 125,000km. The car had to be towed to the Ford dealership where we had bought it as a factory-refurbished vehicle with 45,000km. I also bought the three-year extended manufacturer's warranty, but I was told the plugs were considered consumable items and not covered. I'm at a loss as to how this could have happened. A Ford dealer had regularly serviced the car and had noted on all service records that the fluids had been topped up.