Added several hours later

Where can I go to report this kind of behavior

https://gyazo.com/010ac8abf73007b88191972d1875c8e8

I was added by this person several hours after the match had ended and was spammed with messages like the one above and this

https://gyazo.com/3cb46d6ea12df29fd5c0daff8902c8d9

https://gyazo.com/89c92d6ef6f1ad5b4a0e829e2ef0d11b

https://gyazo.com/205e4f2b205287ea9dce413161b14270

https://gyazo.com/c639a3bee86d0d8572fd13b0eb8b22de

https://gyazo.com/3649fcdc7e52df19d347fa5fcf36b04e

Obviously there is something wrong when you cant report them and the only other means of reporting them, basically links you back to the forums. I dont know what to do but I know this is very unacceptable.