Like a lot of other owners I had the wheelwell leak.
I checked the sunroof tubes, and cleaned them out, but they weren't the problem. What I did initially was to clean all the rainwater out of the wheelwell, remove the spare wheel and leave kitchen paper towel on the bottom of the well to see how much was coming in.
Next, I found that rainwater appeared to be coming from behind the drivers side "boot area" carpetted side panel, somewhere. So, next job, take out all the drivers side back end inner panels so that I could see the bare metal behind. Again, the use of kitchen paper gave a clue as to where the rainwater was coming in. There was always water lying in the round exhaust bracket bushing thing. It had got quite rusty, and the underside of the carpet/insulation panel [for want of a better word] was very wet.
Next was to follow advice from guys here - the first thing that I tried was to take off the rear hatch seal, bend the metal edge, as suggested on this forum, grease and refit the seal. That didn't work, but it did seem to reduce the amount of rainwater coming in. The wheelwell could be dry for days, or even weeks, but then after heavy rain there would be perhaps half a cupful of water.
I had a good look inside the bodywork cavities just behind the rear lights as the water seemed to be running along a horizontal boot panel, but there was no obvious leak. There was no water coming in from behind the rear lights.
In the end, I bought a new rear seal [about £120 if I remember - it was only last June !!].
I then followed all the advice, and I ran RTV all around the "V" in the seal and starting at the bottom edge made sure that the seal went around all the bends and edges, and was firmly seated. A bit of a messy job.
The last thing that I had to do was to do some work on the lower edge where the spring loaded plastic panel is fitted. It was obvious, on my vehicle, that the lower edge had been damaged at some point, possibly by having something heavy dropped on it. the plastic panel had been rescrewed with m4 self-tapping screws in new positions. I used Isopon and filled in all of the new screw holes and bought new, correct m8 screws that were originally used. Then, I retapped the original holes and then refitted the spring loaded panel, using more RTV in the screwholes and putting some onto the screws to seal the threads.
I then left everything out of the back of the vehicle so that I could see immediately if there was any rainwater getting in. In my case I had sorted it out. I left the back bare for about 4 weeks, and having refitted everything I have had no rainwater getting in.
I have to say that it is a really frustrating process, and I don't actually know just which option solved the leak !! But I think that the first thing is to remove all the carpet/insulation panel from the boot area so that you can see where the water is lying, or perhaps even coming from.
Pierre3.