Forgot about this post, I should've followed up. So my problem ended up being the rear spoiler. The upper brake light was replaced, still leaked eventually the dealership ran some silicone around the spoiler and job done. Didn't think spoilers were bolted on so not sure where the water was getting in but it git fixed. To be honest any dealings that I've had with my local dealership has been pretty shoddy always trying to get out of warranty issues, telling me it may have to go back to the original dealership (250 miles away) etc and always a tad arrogant.
