My triton opal shower?

My Triton Topaz T100i is giving trouble again, in that now it won't switch ON, no water comes out of it, and the Indicator shows " Low Water Pressure"!!!

If the answer is straight forward then please indicate what requires to be done please?

However, if not, could you then inform me of which current Triton Shower Unit will replace the Opal T100i, being "exactly" designed with identical measurements- to directly fit the pipe-work - i.e. the 'exact same' foot print, and therefore -WITHOUT ANY PLUMBING work - what-so-ever please? [A simple one for one replacement for both plumbing connections and wall screw fitting/attachment?]

N Wilson Jones
July 2010