Buying a Skin Twice?!

So recently I bought 35$ worth of rp, leaving me with 5046 (including the amount I had). I bought master chef Tahm Kench which obviously left me with 4071 rp. Then I played a jax game for fun, then bought SKT T1 Jax. This should've left me at 3321 ip, but instead it left me at 2571 rp which is subtracting 750 more rp. I don't think its fair that I bought a skin that for more than it is worth and to put it in simple words, I want my rp back.

TinyPic link for RP Purchase history: http://tinypic.com/r/idykab/8

Tinypic link for Skin/Champion purchase history: http://tinypic.com/r/2dhgp5j/8