Overheating and Auto box

Richie, I'd get the vehicle off to an Auto service center to have it looked into.
There are separate cooling systems for the engine and auto box, and unless you were towing or hard, slow 4x4 work, I wouldn't expect the auto to overheat.
Hows the transmission fluid look and smell?
Is it a dirty brown and does it smell burnt?
There's not much you can do yourself to an auto to adjust things. it's best left to the experts.
Get a credible business to look at it ASAP or it could get expensive.

Best wishes mate.

Ken.