Windscreen washers again

Got my Superb in December and had the first long journey last week. Motorways were wet with lots of salt and I found the washer jets to be really poor and practically useless on the rear screen of my estate. Been to the dealers today who would only suggest replacing the jets (at my expense) and they seemed to think that the replacements would be the same jets as already fitted (ie pistol type). I've looked at various threads on here and I'm a bit confused. I've looked at Ebay where there are numerous options but only one or two are deemed suitable for my Series III car despite having the same part number ( 5M0 955 986 C 9B9 ) as all the others which fit the Series II. So to the questions. Are the jets from Series II and III the same, will any jet with that part number fit my car?. Also. the rear jet seems to be built into the rear brake light (stupid arrangement or what?). So is it possible to replace this jet separately or would it require a whole new brake light fitment with possibly no improvement on the existing fitment.

John M