Can't Purchase RP?!

Hello, for the past 2 days i have been trying to purchase rp so i can buy one of my favorite champions and their best skins (the harrowing skins) but every time i try to it says i have exceeded the maximum number of attempts.....even though i just logged on. I attempted to buy rp before the event started so i could buy right away but the same issue occurred. I am not sure if it is a bug in the client it-self or if the recent patch messed it up, but i would really appreciate it if this problem were to be resolved. Thank you.