Scirocco Central

Hi there I have a 2008 2.0 tdi 140 scirocco and have noticed my cap that sits over my rear window wiper has gone missing/been stolen... So now the nut is open to the element and when I use my rear skoosher it shoots backwards away from the window.
Can anyone recommend a new cap/nozzle that I can use as I've seen so many varieties. A link would be fantastic and a great help
Thanks.