Every now and then I post the same. Last time I wrote up detailled instructions was perhaps in "Blatant cheating but you cant call it cheating" on page 3 of Catan forum.
I have reported several cheaters, always successfully.
I quote:
That is what the reporting system is for. Go the players profile, click "Report this player". If you are asked about the problem, choose "Show all" such that you can see all options and choose "XXX uses several user accoutns to gain ELO-points". In the next option choose "The accounts are playing against each other to cheat the ranking system". Then you are asked for the other players account(s) that cheat together with XXX. Please add all the game numbers of fishy games and very specific details why it is obvious they collude. Add move numbers and statistics (e.g., in 30 instances in games .... the robber was placed 28 times on the 3rd player, only twice on the colluding players, OR the two players trade exclusively with each other in games ...).
Add at least 5 suspicious games (that you analyzed) in the moderation report.
Whenever I did above procedure the respective players have been moderated and their ELO has been reset to 100. Sometimes even harsher moderation penalties have been awarded. It is not necessary to prove if it is indeed 1 player with 2 accounts. Even it is two players that collude over several games that it has an affect on their ELO, your report will be successful
