Transmission Fluid Leaking problems of the 2005 Mercedes Benz C Class

A o-ring connected to the transmission started leaking out transmission fluid after my wife drove the car in the snow, the back tires had some traction problem due to the wet snow earlier. Once the car reached home, transmission oil was dripping onto the garage floor. The car has less than 25k on it, in mint condition. She was told by our neighbor that she should not drive it until the problem is fixed. The was taken to the shop and fixed in January when I returned from my oversee mission. The mercedes shop indicated it was a defect in the o-ring design and that a better replacement o-ring was installed for a hefty price since the warranty on the car ended the prior month. I did some research on the web to see if this problem was common given it was a design defect in the o-ring. To my surprise I found this was a common problem that Mercedes Benz refuses to acknowledge. Had she been driving the car she could have ended up damaging the transmission and worse gotten stranded somewhere. I think this defect needs to be investigated further to ensure safety of the drivers of the vehicle given this was not an isolated incident. Others on the web have reported similar problems.