Hi guys, I have a xr6 turbo ute ba 4 speed auto,only 281kw @ wheels, Driving to work today and was sitting about 100 cruise control on, Car went to drop back a gear as I was going up a small hill then a loud humming noise, then it clunked into gear,then tried dropping back a gear and done the same thing,so I pulled over for 10mins and went to take off again,then the auto could only find 1st and 2nd, tried tip tronic and that did not work, Any help? Or is it time for a new gearbox, If so what should I get?