Can you get a refund either RP or IP on a champion if you do not like them?

If you e-mail riot support they are usually willing to give ONE refund if you ask nicely, but this is rare because they are not supposed to.

There is now in-game support for refunding up to 3 champions or skins, no need to contact Riot support. You get back the same currency used to purchase them (RP/IP).

Here are the full limitations, according to Riot's page:

• You only get three refunds per account, per lifetime
• You can only refund skins and champions, not runes, boosts, or bundles
• We can only refund a purchase that you’ve made in the last 90 days, so no hocking last year’s promotional skins back to us!
• If you own a champion and some of their skins, you need to return the skins before you can get a refund on the champion