Either message them on there wall or contact support@athinkingape.com and tell them then game your playing PIMD, your username and the issue and if you can take a screenshot but right now just block them
A moderator will only silence a player if they've broken the ToU or RoC. If you believe some one has, you can wall a moderator, all send a screen shot to support@athinkingape.com
What about dealing with someone you have already blocked but continues to stalk you and harrass you, even after you have told that person to leave you alone?