Ripped off in the Store

I already sent an email to Riot Support, telling them about the what happened. But basically I saw that Lord Mordekaiser was on sale and decided to buy it with RP. I went to his champion page and bought the skin for what it showed me as 487 RP. However it charged me for the full amount and left me with 95 RP. In the Purchases tab of the store, it says I bought it for 487 RP. I thought I'd post here anyways in case anyone else was dealing with this. Don't know if its a bug or not.