Ranked game -> no points

Hey... So yesterday i played a ranked with my bro, i usually take +20 LP when i win and -15 when i loose, so i won but after the game it only gave me +9 LP.... And yeap now im 91 points, if riot games didnt bug i would now be on promos :) sorry for my bad english!! Give me my points RIOT thats not fair at all....... you just lost my promotions (guys if you know any informations about this please share them with me cause i need to know what happened ty).