IP purchases not debiting the account the worth of the purchase.

Had about 5200 IP and bought Draven (4800IP) which brought me down to about 400IP. I saw this with my own eyes. Played a game and went back to the store and now I have about 5200IP again and Draven is unlocked to play. Thanks for the free IP, but this is not correct. I can garner an unfair advantage over other players if this bug is reproducible.