Spam summoner accounts

In the past I have received friend requests from random summoner accounts (of different names) and, as I'm not the best at paying attention to the names of the people I play with, I've accepted the first one I received. As soon as I accepted the request I got a message asking me to go to some outside site to pay for something. Since then, I always look up the name before I decide whether or not to accept (the spam accounts are always lvl 1 with no XP). The requests never stopped, they used to be maybe once every 2 or 3 weeks, but now I'm receiving 2 or 3 of them a day and its really getting on my nerves. I know I'm not the only one this happens to because some of my irl friends have had the same problem. Is RIOT aware this is an issue for some people? Does anyone know if there something I can do to get it to stop?