Thingwala

The Thingwala guys have come back to me, and say the Geyserwala will plug straight into my old 2 digit Geyserwise MAX.  So all questions resolved.
Impressed at their response - I sent them email about ten minutes ago and got an immediate reply - not bad for 23h00 on a Tuesday night.

Evening Folks
After seeing a post about thingwala and getting your geyser connected to the internet, I purchased a geyserwala connect.
The install was easy enough after watching the install video, my biggest delay was that the data cable was a little short, the installers of my solar geyser glued it to the wall. The Wi-Fi connects easy enough, but just be aware, if your IP addresses does not start with 192.168.x.x, you will need to set the IP in manually on the geyserwala.
Once online and the online token was installed the geyserwala worked flawlessly, I set in the setpoint temperatures and setup the timers and could not be happier.
The service was awesome. If you looking to future proof your geyserwise unit, geyserwala connect is the way to go.

Thanks @Thingwala. 
I waited a bit before replying here to see if any bugs pop up. No issues whatsoever.
Really happy with your product and can't recommend it enough. Thank you again.
 
Now for the next project.... ITS heatpumps....😉

@Ken I buy the geyserwala. 
The guys are willing to work with you if you have problems and its simply a superior product.
I'm very happy with mine.

Thank you, I just got one!

I went the Thingwala route since they were willing to work with me to ensure compatibility with my older TSE model. 
Home Assistant integration was pretty straightforward and On/Off element functionality and water temperature is now available to me in Apple HomeKit via the Homekit Bridge, and additionally other entities that can also be exposed and used if required in HA and/or Node Red.