sixers

I checked the seals and cleaned them, poured water down the sunroof drains and the water dispensed at a fast rate to the wheel wells. The sunroof glass covers the front driver and front passenger side. The second row seat and trunk are covered with metal body. The sunroof leak is large and located at the back side of the sun roof closest to the second row. It only leaks when the high powered jets at the car wash go over the sunroof. Unfortunately the amount of water that leaks through each wash has been enough to stain my headliner. Any ideas in how to fix this issue. A Benz dealership told me I would have to purchase the whole sunroof setup which costs a few thousands dollars as the seal is not sold separately according to them. Any input would be much appreciated.