the fix is basically, pull off the vent cover on the passenger side, pull out the rubber foam, you will see where the sun roof drains are located, tear off the part of the rubber that covers the drain, and put it back. That is what the dealer will do. Btw, if you LR3 is out of warrantee, you will be charged.
A side note, there are many electric/electronic connections under your carpet on the passenger side under the seat and under the plastic liner btween the carpet and doors. Something else I found out, if you take your LR3 in the water as advertised, you need to remove your spare tire, and look on driver side you will see another electric/electronic connections that needs to have water resistant spray applied. It's beyond me why Land Rover would have this connection below the advertised under water mark.
I found all this out this week with my LR 3 in an independant dealers shop. I had much corrosion in all these connections.