Waterproof bags?

I first bought one of these new double strap lightweight stand bags last year.
The material suggests nylon or strong parachute material that water would simply run off, but in fact the very opposite is the case. Water seems to 'stick' to the bag and eventually seeps in -making the black internal colour appear through the golden outer colour - and the straps become like wet sponges which soaks your shoulders due to the weight of the clubs.
It is a Wilson which seems a good make, but I need something a bit more practical for the Scottish climate!
I play Mizuno irons and Maxfli M3 balls so would tend towards these brands although I would obviously coonsider others for the right bag. Help!