Volkswagen Touareg Brake Pads and Rotors May Wear Out Prematurely

I bought this car used with approx 19,000 miles. The first time I took it in to the dealership for a instrument panel issue I already had blackened wheel bases for all four tires. I've taken the car in at lesast four times since I purchased it in August, 2011. I took it in last week (Dec., 2012) since the instrument panel advised to :"Check brake pads." The Service Center attendant told me that the blackened wheel base is an indicator of brake pad and rotor problems or need for replacement. If this is the case, why wasn't I advised of this issue back in September, 2011 when I first took the vehicle in for another issue and all of the wheel bases were blackened then and, for that matter, each of the three times when I subsequently took the car in to the VW Service Center? Needless to say, I feel that this issue is something that VW doesn't wish to disclose to its customers. (Not very honest, right?)

Just wear and tear, extreme brake pad dust, complained since new they say it is normal