I would check with refrigerator/appliance repair people too. The refrigeration components on a chiller are fairly similar in size to a fridge. I wish I could be of more help.
Can you tell if the chiller is actually functioning and the controller is just screwing up (i.e. hot air is coming out of chiller, but it just turns off too early, etc.) or does it seem like the problem is in the chiller? If it is just a controller issue someone in SA should carry a controller and maybe someone with a little electrical knowledge could figure how to hard wire the thing on for a while until you were able to procure a new controller. These are just random thoughts I would think if I was in the situation.
I am fairly confident that you have taken all emergency measures including turning off lights, bringing in fans, etc. I don't know about in SA, but here in Austin this morning it is nice and seasonably cool (~65 degrees). Opening a window and blowing some of that cool air across the surface of the water in the sump might help some. Good luck.
144 G Half Circle Mixed Reef, 240G FOWLR