I have had a B-96 and also a Tau-7 which I bought from May of London, they both came with the SodaStream adaptor. I suggest you contact them for one, if they don't have one they will be able to tell you where you can get one.
Tau-7 is a superb pistol, wish I had not sold mine, great design, sweet trigger, easy to use.
http://www.mayoflondon.co.uk/