Yet more problems with my RR. After finding the DVD sat nav filling with water I took the rear inner plastic from the nearside rear pillar to discover water leaking down from a weld/joint near the ceiling liner. I have replaced the boot rubber, but made no difference. How is water getting into and behind this joint? Could it be the tailgate hinges are leaking? The joint doesn't even look particularly well sealed. I need to sort this before replacing the repaired sat nav, many thanks