1 - They have multiple e-mail addresses for different situations.
2 - You're not going to get refunded RP just because those champions did not meet your expectations. I've heard of them making exceptions for like one or two people, but you are probably not going to be one of them.
3 - The support e-mail address is firstname.lastname@example.org
If you had some kind of legitimate problem with your RP, then go ahead and e-mail them.
But if you just think that Leblanc and Twitch are underpowered, too bad. I hate it when people try to make themselves exceptions to rules because it encourages other people to make themselves exceptions and it will ultimately undermine Riot and ruin the product for everyone else in other ways.
To add on to what Calm said, I think they give one refund per account, than you will never ever get a refund again. I gotten two refunds before. One because I accitentally clicked RP to buy Alistar, and they gave me my RP in turn for 1.3kIP. The other was a refund on Malazhar's prince skin, that was because it was announced that it was goin to be on sale around 3 minutes after I bought it.
"I've got something, uh a headache with pictures!" "An idea?" GT: Circle6
Both of those characters are actually decent, I'd save my "second chance" for a character with absolutely no hope of ever being good. Like Jax or something. (Of course, a fed Jax wrecks, I just needed an example that wouldn't get me flamed too hard.)