MYSQL Events (cron job)

I have a chatting system working fine. Two persons are chatting, one is visiting, and the other is a representative. when a visitor tries to chat, a random representative is selected from the online representatives. What you need to updated: if a representative is already chatting with someone else, he should not be assigned to anyone else. if a representative does not responds for 2 minutes, he should be made offline by force. if a visitor does not responds for 2 minutes, he should be made offline by force. and anything else to make the chatting system perfect. if a bidder does not explains the problem in his bid and his suggestions, his bid will be ignored and will be marked as spam