Unhappy Customer

I am driving a C*** model which I bought at Mercedes Benz Century City. I service my car at Mercedes Benz Century City only from day one. Getting to the point, my day time lights stopped working because they built moisture inside and that moisture turns into water. I took the vehicle in for service couple of years ago and one day time light was replaced without a problem. Now both day time lights are not working and when I took the vehicle for service I was told they will not charge them before I pay R14 000 but one was charged before as the vehicle is under the plan. Why this time around is a problem as the vehicle is still under the plan?