I have come across this as I am sure many have where you purchase an item but yet you already spent your three credits given. Now many will say "well you used your credits and that is that" but we are all human and make mistakes. I would like to suggest that there be a 5 minute grace period after purchasing an item so that players who truly did accidentally purchase something from the store be able to rectify it and not be penalized by the three credits,and that the three credit system should still exist for past purchase that fit the time frame given by Riot.
Thank your for your time.