Here's my opinion for a possible cause for the decline in...

Here's my opinion for a possible cause for the decline in sales.
They originally sold into the market as being a 24hr / 30 day protection system register with TGA registration (re: ARTG 331860). The registration has changed and the 24hr / 30 day claim has been removed.
Other competitor's such as Zoono and Duropax have also lost the 24hr / 30 day claim.
I believe the regulators made them all provide testing to confirm the durability claim and only a select few that had better formulations made it through. (re TGA's "Proposal for clarifying regulatory requirements for residual claims for disinfectants")
There are other competitors in the same market that still have a 24hr claim for example, Siqura Extend (re: ARTG 344850)
The top end (price) of the disinfectant market requires regulatory approval for claims.
With no regulatory approved durability claims they are just another disinfectant with low level claims but a high price tag.