Hi Robbie, Sorry this reply came a bit late. I had the same problem as you ever since I bought a 2nd hand c5 (2008) in 2013. The problem lies with the drainage being choked by leaves/crap that falls through the plastic guard under the wiper. The issue can be fixed by yourself. Just need to 1) remove the wipers, 2) remove the plastic cover under the wipers (whatever its called) 3) remove the wiper motor 4) dig and clear out the junk that's trapped and clogged up the drain hole small hole with a rubbery flap under the wiper motor 5) replace everything back For me, the issue was aggravated by the white foam/mesh (that was supposed to filter the cabin air intake) breaking off and covering the drain hole and further trapped the rotten leaves that fell through plastic guard under the wiper. I suppose a way to solve the issue permanently is to install a finer insect mesh under the plastic guard to prevent leaves from falling through. Havent got around to it though. Hope this helps the rest who had the same issue.
