It has happened to my clan frequently in the past 3 months, with myself, my deputy owner and other high ranks being impersonated. Sadly one clan member fell for it and lost 200m. It seems to happen very frequently while the unknown guest is still in the cc, and as soon as people ask about it in the cc the guest will leave and the impostor account will appear offline right after.
Only thing I can say is warn, warn and warn. Tell people to add the higher ups, and if they get a pm from someone not added, then it's not someone in the clan staff. I realise it's hard for Jagex to do something about it, but if possible try to find the people responsible. Not just the bogus accounts themselves, those are not of any interest. Some of those added to the clan ban list haven't even changed their names yet. I'm talking about mains benefiting from this scam being banned.
12-Sep-2016 13:42:42