So the fluid level was checked this morning and is all good. Asked the mechanic who did the service and he did reset the gearbox adaptions.
Next step; the automatic transmission specialist recommended a VW/Audi specialist near me who i visited and he discussed checking pressures and things, same as Brunswick Garage did. So as soon as i get it booked in and checked from them I'll hopefully know where to go next.
Ps. The transmission specialist explained the issues with using the additive i discussed, and i decided against using it.

 

I've never used the Lucas stuff for transmissions. I hear good things about the oil additive I'm reluctant to use items like that in automatic transmissions. But if push came to shove, the Lucas stuff would not be out of the question in my book.