Many moons ago Kyral I had this problem with a Vauxhall Polo. Upon investigation it was found that the seal along the bottom of the wind down window was about a quarter inch too short and the water was going down slowly between the window and the door and filled up the plastic membrane inside. When that was full it then overflowed into the door space and seeped through and under the carpets. One point, make sure they cure it before the winter because I can tell you it is no joke getting into a car and trying to drive it when the footwell is an ice rink!!! Anyway, good luck! :0)