The best thing is to do is to stop the vehicle on the middle of the road if he is coming face to face. But for this you have to see the vehicle well in advance.
Did this happen around Rajagiriya, Parliament area? if so YES I also have seen this idiot, never gave the way for him, and kept going as slow as possible on the middle of the road.
It is not a fault, same thing happens in our N16, I think its a safety feature, incase of you forget to lock the doors or activate the security system manually the security system gets activated automatically after some time.