There's a bunch of Chatswood shops with a shower.

Mali Mali 3/6 Help St
Bodycare 200/1 Katherine St (enter from Thomas St)
Spectra Studio 24 Oscar St
Chatswood Oriental Health 29a Oscar St (hand shower only - ask)
Moments of Peace 55/47 Neridah St

Attractive girls, NHJ (and more) available in all these.