I have a similar issue that occurred when travelling on corrugated roads and through water above a certain depth. Turned out when the lift was put in, the shop disconnected a clip that holds that ABS sensor wire still, and didn't put it back together when they finished. The result was the ABS...
It might be difficult to get to Australia, and I haven't even got a built Jeep yet (hence the photo - it COULD be my jeep - I've ordered that colour) but I know it's a modders vehicle, and what better way to kick it off?!