There's nothing much to say. You raised the question and answered it yourself.
We can't write each and every thing. It should be assumed present already, even if/when not explicitly written. There are more than 30 ways by which a member can abuse and manipulate points, ranking and the payment system. But, since they are not written anywhere, it doesn't mean they doesn't exists. Of course they do, but writing them will expose those loop holes to mass audience.
I accept that I had been posting 1-2 answers every session to accumulate consolations and redeem it whenever necessary by coming in top 20.
You may say that this is not sole motive of consolation, its for those who are unable to come in top 20, so, we give them consolation so that they can be motivated to come in top 20 next time.
See, how well you know that you have abused it intentionally even after knowing the purpose of the consolation very well.
Consolation is meant for those who are unable to come up in top 20 even after investing their time and effort, so that they can be motivated to try for the next session again. It is not meant for "Hey, take Rs.200/- from us each month for posting 2 answers".
"no prior warning is totally ridiculous."
We wish someone ever say - "Hey, Support no prior warning before increasing points is totally ridiculous. You should have warned / informed / intimated me instead of directly increasing it."
And, by the way, don't worry that you are the only one who got penalized in such a way. Such things keep happening. Last month also 2 were penalized because of the same reason, and their amount was double and triple than your amount. But, none of them said a single word, because they knew it's wrong and silently accepted it.