where is the drain plug on radiator to flush on 99 holden vectra 2.5lt

No references to this vehicle in out databas or in Mit1 if its me I'll disconnect the lower hose and drain thru there and also faster that way-

alarm bellsshould be ringing really loud for you get a compression test done asap,,,urgently it wont cost you anything but your symptoms you describe happened to ours. heres the thing, these cars dont registar any warnings regarding overheating, but you mention about water loss ur something to do with it...damn get this check done pronto as the car comes with weak tolerances for overheating withoyut you knowing and wind up with a ceacked head