Good luck with that line of thinking. NCSoft owes you ...nothing. If they decided to shut the game down right now, you have no re course what so ever. If they want to delete you toons, again you have no say in the matter. You probably should read the Lineage 2 User agreement.
As for your pizza shop example. There is no such "law" stating he has to honor anything. If you order the pizza thinking it was on sale and he refuses you choice is to pay for it or leave.
P.S. You sound like a spoiled child.