ConradDeWet

Well, yes... in one of the posts in this forum, someone mentioned Dan, from DC Rebel (https://www.dcrebel.co.za/). He was extremely helpful! 
Firstly, you need to know that the Dyness 9.6kWh "Powerbox" as they call it, is nothing more than 4 "Dyness 2.4kWh LiFePO4 Batteries", packed in a lovely wall mountable case, with the batteries mounted two at the top, and two at the bottom. 
To access the DIP switched, you need to unscrew the white case:

The (unreleased) documentation says the master battery (bottom front) must be set to 0110 in order to talk to the Growatt-SPF. However, this didn't seem to make any difference to me.
Dan was kind enough to bring round a "special" cable for the Dyness to the Growatt (an orange one), however we didn't use the "Li" settings of the battery type (menu option 05) that requires the BMS communication to be in place anyway.
We used the User settings for battery type (menu option 05), then:
19 (Charge Voltage) = 52Volts
20 (Float Voltage) = 52 Volts
21 (Max Dischange)  = 45 Volts
With these settings in place I have not had any more issues - except it can be a bit strange as the outer case lights go orang some times, Dan says its fine, he called it something like "balancing".
It's been in place a few days now, and after I put these settings in, it all seems to be working fine.